Progress 10/01/99 to 09/30/05
Outputs
Best weed control strategies for green-shelled and dry beans were 1) trifluralin preplant incorporated and 2) metolachlor preemergence, both followed by postemergence bentazon and sethoxydim. Dry bean yield was improved from 69 to 88% with these strategies. Pendimethalin followed by bentazon and sethoxydim, provided the best weed control in a corn-bean rotation. Root exudates from Echinochloa colona promoted root nodulation of bean plants. Coffee: Trimming living mulches (pond peanut and dalisgrass), every 4, 6, 8 and 12 months after coffee establishment, reduced weed cover from 41 to 56 percent the third year. Plant height and canopy diameter of coffee groves were not influenced by trimming the living mulches after three years. Living mulches were insufficient to suppress spreading of Commelina diffusa around coffee. Root Crops: Either ametryn or clomazone preemergence, followed by clethodim postemergence, controlled grasses, as did plastic mulch plus paraquat
directed postemergence to yam (Dioscorea alata).Yam yield with plastic mulch was similar to that of conventional yam planting. Plastic mulch plus paraquat controlled 100 percent weeds in sweet potato, better than preeemergence ametryn, clomazone and dimethenamid followed by clethodim. There was yield response to herbicide treatments in sweet potato. Vegetable crops: Disc incorporation of mature plant residues of Mucuna deeringiana, Cajanus cajan, Sorghum bicolor and Cucurbita moschata suppressed nutsedges more than removal of residues from soil surface. The first year of rotation, onion grown after C. moschata produced 63 and 70 percent more yield than after C. cajanus and S. bicolor, respectively. Halosulfuron-methyl resulted highly phytotoxic to onion, reducing yield; the potential use in this crop must be dismissed. Oxyfluorfen was safe and effective for weed suppression in onion. Halosulfuron-methyl controlled purple nutsedge efficiently with no phytotoxicity or yield response in
calabaza (C. moschata).
Impacts
Weed management strategies were developed and are available to increase bean production and reduce imports into the island. Suppresion of weeds by living mulches may be adopted as an alternative practice to reduce herbicide applications and reduce chemical contamination in upland agro-ecosystems. Oxyfluorfen at 10 days after onion emergence could be integrated as a new tactic to reduce early weed interference more than conventional application at 15 days.
Publications
- Lugo-Torres, M. de L., M. Diaz, H. Torres and C. Almodovar. 2005. Secuencia de herbicidas y uso de cubierta plastica en batata. Abstr. p: 40 en: Memorias Reunion Cientifica Anual-SOPCA 2005.
- Lugo-Torres, M. de L., M. Diaz, H. Torres and C. Almodovar. 2005. Herbicides and plastic mulch in yam (Dioscorea alata). J. Agric. Univ. P.R. 90 (1-2).
- Semidey, N. and L. E. Flores. 2006. Nutsedges (Cyperus spp.) control by cover crop rotations in onion. J. Agric. Univ. P.R. (submitted)
- Semidey, N. and A. Gonzalez. 2006. Preplant and postemergence herbicides for weed control in direct-seeded and transplanted calabaza (Cucurbita moschata). Department of Crop Protection-Unpublished.
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Progress 01/01/04 to 12/31/04
Outputs
No differences in weed control and acceptable tuber yield were found for the following weed control treatments in yam: 1) plastic mulch plus paraquat; 2) ametryn (pre) followed by clethodim (poe); 3) clomazone (pre) followed by clethodim (poe); and 4) diethenamide (pre) followed by clethodim (poe). Coffee: Trimming applied to living mulches (pond peanut and dalisgrass) every 4 to 12 months reduced weed cover after two year of mulch establishment. Weed cover was reduced more with trimming performed every 6 and 12 months than every 4 and 6 months. Plant height and canopy diameter of coffee groves did not show significant differences after one year of trimming. Weed density decreased in all trimmed living mulches by May 2004. In July 2004 weed population increased more when trimmed at 4 to 12 months. Vegetable crops: One M.S. Thesis related to application timing of oxyfluorfen and halosulfuron-methyl in onions was completed in May 2004. It was concluded that halusulfuron
may not be recommended for use in onion because of phytotoxic damage in this crop. Oxyfluorfen was a safe chemical for weed suppression in onion. One experiment was established by mid-December 2004 to evaluate purple nutsedge control with halosulfuron-methyl in calabaza.
Impacts
Suppresion of weeds by living mulches may be used as an alternative practice to reduce the use of herbicide applications, thus reducing potential contamination of chemicals in upland agro-ecosystems. Application timing for oxyfluorfen at 10 days after onion emergence reduced early weed infestation 89% more than conventional application at 15 DAE.
Publications
- 1. Lugo, M.de L., M. Diaz, H. Torres and C. Almodovar. 2004. Uso de cubierta plastica versus herbicidas pre-emergentes en name (Dioscorea alata). p: 48. Resumenes Reunion Cientifica Anual SOPCA 2004.
- 2. Ruiz. C. J. 2004. Tiempos de aplicacion de oxyfluorfen y halosulfuron-methyl y su control de malezas en cebollas (Allium cepa L.). M.S. Thesis-Univ. P.R.-Mayaguez. 59 pp.
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Progress 01/01/03 to 12/31/03
Outputs
Sweetpotato yield was improved with preemengence clomazone compared to the yield with a plastic mulch + paraquat treatment at Juana Diaz. At this location preemergence dimethenamid was as effective as clomazone. There were no yield differences among herbicide treatments at Gurabo. Average tuber yield was 33,800 kg/ha at Juana Diaz and 21,145 kg/ha at Gurabo. Coffee: Trimming frequencies every 4 to 12 months reduced weed cover after one year of living mulch establishment. Pond peanut and dalisgrass showed more or less the same ground cover. Total weed density was not affected by the two living mulches for the first five months of coffee establishment. Eight months later weed density was suppressed by trimmer cuts of 4, 6, 8, or 12 months intervals. As living mulches increased ground cover, more weeds were suppressed in coffee plantation. Vegetable crops: Postemergence halosulfuron was less phytotoxic to onions when applied at 30 days after emergence (DAE), irrespective
of herbicide rates. The 0.013 kg ai/ha rate was more phytotoxic when applied 20 and 25 DAE. Plots showed higher weed density when halofulfuron (0.013 kg ai/ha) application was delayed until 25 DAE. Application at 30 DAE resulted in weed densities similar to that of handweeding. Halosulfuron at both rates and at application times of 20, 25 and 30 DAE reduced onion yield. Oxyfluorfen applied 5 or 10 DAE reduced weed density more than the 15 DAE application. Oxyfluorfen applied 5 to 15 DAE alone was safe for onion, but the halosulfuron application that followed in the same plots at 35 DAE was highly phytotoxic. Onion yield was reduced by halosulfuron application at 35 DAE.
Impacts
Trimming the living mulches reduced weed infestation in a coffee plantation up to 97% during the first year of establishment. Suppresion of weeds by the living mulches may reduce the use of herbicide applications and potential contamination of chemicals in upland agroecosystems.
Publications
- Semidey, N., E. Orengo Santiago and E. G. Mas, 2002. Weed suppression and soil erosion control by living mulches on upland coffee plantations. J. Agric. Univ. P.R. 86:155-157.
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Progress 01/01/02 to 12/31/02
Outputs
Compared with other weed species and a weed free control root nodule number, nodule fresh and dry weight of Phaseolus vulgaris was promoted by a nutrient solution applied to the root system of Echinochloa colona under greenhouse conditions. Nutrient solution from Amaranthus dubius, E. colona, and Parthenium hysterophorus decreased shoot dry weight of P. vulgaris. Under field conditions of a Coto clay, nodule number of P. vulgaris roots was higher when grown in companionship with Sorghum halepense than with P. hysterophorus or A. dubius. Root Crops: Applications of ametryn, clomazone, and dimethanamide provided good weed control in sweet potato, tanier and yam. Sweet potato yield was not improved by herbicide applications. Coffee: Trimming the living mulches (pond peanut and dalisgrass) every 4 and 8 months enhanced their ground cover and reduced weed growth in a coffee plantation. Dalisgrass established well and presented more growth and ground cover than pond peanut.
Vegetable crops: Preplant incorporated (ppi) halosulfuron-methyl ( 0.027 and 0.054 kg/ha) and trifluralin (1.12 kg/ha) were not effective for general weed control in transplanted pepper. Both ppi rates of halosulfuron-methyl reduced A. dubius density but failed as postemergence treatment at 0.054 kg/ha. Oxyfluorfen at 0.13 and 0.27 kg/ha applied at 5, 10, and 15 days after onion emergence provided better weed control and less phytotoxicity to onion than halosulfuron-methyl (0.027 and 0.054 kg/ha) applied on the same dates.
Impacts
Compared to the natural weed population, living mulches reduced 54 % of weed density thus representing a potential sustainable weed control practice to lower herbicide usage in upland coffee plantations. Even low densities of weeds such as P. hysterophorus and A. dubius need to be controlled in bean fields to avoid negative effect on root nodulation.
Publications
- Lugo, M. de L. y M. Diaz. 2002. Acumulacion de peso seco en las partes de la planta de leren. Abst. Mem. SOPCA. p:32.
- Semidey, N. 2002. Response of pigeon pea cultivars to prometryn, metribuzin, and imazethapyr. J. Agric. Univ. P.R. 86 (1-2): 69-71.
- Semidey, N. 2002. Clomazone and oxyfluorfen as preplant herbicides for Cucurbita moschata (calabaza). J. Agric. Univ. P.R. 86 (1-2): 73-75.
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Progress 01/01/01 to 12/31/01
Outputs
Basic Grains: Preemergence metolachlor provided good weed control in the initial bean and corn plantings. In the corn-bean rotation, metolachlor as well as trifluralin and pendimethalin, both followed by bentazon plus sethoxydim, provided the best weed control after six weeks. In the corn-bean rotation, metolachlor and pendimethalin were more efficient than the combination of bentazon plus sethoxydim (postdirected) and the atrazine treatments (pre or post). In contrast to bean, corn in rotation with bean produced yields as high as in the first corn planting. There were no significant differences in fresh corn and dry bean yields among herbicide treatments in either rotation system. Root Crops: Interference by Amaranthus dubius significantly reduced N, K, and Mg uptake during after 11 weeks of planting. Uptake of P and Ca was reduced by A.. dubius during after 13 weeks. Coffee: Check plots without living mulch had more weeds than plots with the two living mulches
(Arachis kretschmeri and Paspalum dilatatum) during May and August evaluations. The two living mulches covered more ground than the natural weed population present in coffee check plots. Trimming frequency of the living mulches had no influence in weed density after one year of coffee establishment. Vegetable crops: Cultivation of calabaza and glyphosate preplanting provided better control of nutsedges and total weeds in general than clomazone plus glyphosate and glyphosate followed by postemergence sethoxydim. Two methods of planting calabaza (direct seeded and transplanting) had little effect on weed densities, except for the grasses, which were at higher level in transplanted than in direct seeded calabaza. Calabaza yields were not affected by herbicide treatments. Overall, transplanted calabaza produced higher yield (15, 290 kg/ha) than direct seeded calabaza (4, 190 kg/ha). This result indicates that calabaza, when transplanted, may compete better against weeds than when direct
seeded.
Impacts
Transplanted calabaza may compete better against weeds, producing 11,100 kg/ha increase in calabaza fruit yield over direct seeded calabaza. Trimming of living mulches may reduce 80 percent of weed density compared to natural weed population, representing a potential for reducing herbicide usage in upland coffee plantations.
Publications
- Lugo, M. de L. and Acosta, A. 2001. Performance of paraquat and sethoxydim in arracacha. J. Agric. Univ. PR. 85: 63-68.
- Lugo, M. de L., Ortiz, C.E., and Rosa-Marquez, E. 2001. Amaranthus dubius interference in sweetpotato: Effect on mineral uptake. Proc. Caribbean Food crop Soc. 37:43-44.
- Semidey, N. 2001. Estategias de manejo quimico de malezas en Phaseolus vulgaris bajo riego por goteo. Libro de Resumenes del XV Congreso de la Asociacion Latinoamericana de Malezas. 26-30 de Nov. 2001, Maracaibo, Venezuela.
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Progress 01/01/00 to 12/31/00
Outputs
Season-long interference by 15 Amaranthus dubius plants per m row reduced sweet potato yield 96 percent, whereas 30 plants per m row reduced percentage of yield up to 100. Maximum leaf area index (LAI) of A. dubius occurred before maximum LAI of sweet potato. Weed interference was limited to the first period of sweet potato crop cycle. Basic Grains: Grass weeds were significantly reduced by preemergence metolachlor and atrazine, and postemergence sethoxydim during first six weeks. Yield of green shelled beans was not influenced by herbicide applications. Coffee: Two living mulches (Arachis kretschmeri and Paspalum dilataum) planted as covers around coffee trees on May 2000 have not performed well under dry conditions of the mountain region. Vegetable crops: Mucuna deeringiana, Cajanus cajan, and Cucurbita moschata ,used as cover crops either disked or laid on soil surface at Lajas area, reduced nutsedge density compared with that in open plots without covers at eight
weeks after onion planting. Mucuna was the best cover among four covers reducing nutsedge population at eight weeks. Clomazone preplanting injured C. moschata more than glyphosate and sethoxydim at Corozal. C. moschata yield was enhanced with clomazone and cultivation treatments. At Corozal C. moschata transplants apparently competed better against weeds and yielded more (13, 100 kg/ha) than when directly seeded (6,500 kg/ha). The best grass control at three weeks in C. moschata at Lajas area was provided by plastic mulch, glyphosate preplant alone or combined with clomazone.
Impacts
Use of paraquat will replace at least two handweedings in arracacha, thus reducing production cost. Five herbicide strategies are available for bean production. Clomazone weed control provided 6,600 kg/ha increase in calabaza fruit yield over cultivation.
Publications
- Lugo, M. de L., C. E. Ortiz, and E. Rosa. 2000. Amaranthus dubius interference in sweet potato. Hort. Sci. 35 (3). June 2000.Semidey, N., E. Orengo, E. Mas, and L. E. Flores. 2000. Control de malezas y erosion de suelo en cafe con cobertoras vivas en la zona alta de Puerto Rico. p. 115 en Memorias de la Reunion Anual de la PCCMCA, San Juan, PR.Semidey, N., E. Acevedo, and L. E. Flores. 2000. Herbicide strategies for weed management in green shelled beans in Puerto Rico. p.29 In: Abstracs Annual Meeting CFCS, Santo Domingo, Dominican Republic. 27 August to 1 September 2000.
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Progress 01/01/99 to 12/31/99
Outputs
Root Crops: Plant dry weight of arracacha was reduced linearly at the rate of 32 g/m2 for each week of interference (0-40 weeks after planting). Harvested plants declined at the rate of 185 plants for each week of interference. In another arracacha study, paraquat at 0.56 kg ai/ha applied twice gave 100% weed control, and one late application provided 84% of weed control. Sethoxydim at 0.34 kg ai/ha gave 92% grass control. No differences in yield were found between herbicide treatments. A tanier experiment was established in 1999 with ametryn, oxyfluorfen, imazethapyn, paraquat, glyphosate, and sethoxydim as treatments. Beans: Strategy 1 = STG 1 (trifluralin at 0.75 kg/ha, pre plant incorporated (PPI), followed by bentazon at 0.75 kg/ha, POST and sethoxydim (0.37 kg/ha, POST) and STG 4 (imazethapyr at 0.06 kg/ha, PRE, followed by bentazon and sethoxydim, POST) significantly reduced weed density at Juana Diaz and Isabela in sprinkler irrigated beans. STG 2 (bentazon at
0.75 kg/ha, POST followed by sethoxydim, POST) at Isabela and STG 3 (metholachlor at 2.8 kg/ha, PRE, followed by bentazon and sethoxydim, POST) at Juana Diaz provided good weed control and yield of dry beans. Strategies 1 to 4 provided excellent yields of green shelled beans at Juana Diaz grown under sprinkler irrigation. No phytotoxicity was detected with sprinkler irrigation at the two sites; however, STG 3 caused 20 and 40% injury at three weeks with drip irrigation at Isabela and Juana Diaz, respectively. The phytotoxicity was caused by the preemergence application of metholachlor (2.8 kg/ha). The best control of grasses (93%) at Isabela under the drip irrigation system was obtained with STG-1 and STG 5 (trifluralin at 0.75 kg/ha, PPI followed by mechanical cultivation at fourth week). There were no significant differences in green-shelled beans at the two sites using drip irrigation. The best yield of dry beans was recovered from STG 1 (2,197 kg/ha), STG 3 (2000 kg/ha) and STG 5
(1950 kg/ha) at Isabela. At Juana Diaz, STG 1 provided the best yield of dry beans (1,160 kg/ha). Onion: Neither purple nutsedge density nor onion emergence was affected by four cover crops (velvetbean, pigeonpea, sorghum and calabaza) grown previously to onion. Velvetbean and sorghum reduced grass density at two weeks after onion planting and broadleaf weeds at nine weeks. Weed suppression by the cover crops did not improve onion yield because of purple nutsedge intereference. Coffee: All five living mulches (bahia grass, dallis grass, carpet grass, Alexander grass, and pond peanut established in coffee plantation during 1996 suppressed 83 to 93% of weeds compared with glyphosate used as control. Pannicum maximum dry weight was better suppressed with dallis grass, pond peanut and glyphosate than with bahia grass and Alexander grass.
Impacts
Improved weed management may allow an increase in bean plantings and reduce imports of $15.0 million. Living mulches in coffee plantation can be used for weed suppression and soil erosion control to reduce herbicide usage, production expenses and improve crop productivity. Cover crops may suppress purple nutsedge in onions, improving onion yields more than 50% and total production on the Island.
Publications
- Lugo, M. de L. and Acosta, A. 1999. Weed interference in arracacha (Arracacha xanthorriza). Proc. Carib. Food Crop Soc., St. Lucia.
- Semidey, N., Gonzalez, A. and Aponte, A.. 1999. Application timming for clomazone and oxyfluorfen in transplanted cabbage. M S 98-17, J. Agric. Univ. P.R. 83(3-4): In Press.
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Progress 01/01/98 to 12/31/98
Outputs
Field experiments were conducted to evaluate weed management practices with five herbicides in dry beans and four cover crops for rotation with onion. Metolachlor, trifluralin, pendimethalin, and bentazon in sequences with sethoxydim controlled 100% of the grasses in dry beans. Bean yield did not differ significantly since all of the herbicides reduced weed biomass and potential loss in grain quality. The evaluation of living mulches in coffee showed that grass weeds were suppressed more in dalisgrass, carpet grass, Alexander grass, and pond peanut than in bahiagrass. By January of 1998, all five mulches controlled from 77 to 95% of the broadleaf weeds. This range of control is comparable to that of standard glyphosate treatment. Mucuna, pigeon pea, grain sorghum, and calabaza, which were grown as cover crops for six months and later incorporated into the soil before planting onion, reduced purple nutsedge density 37% more than that of open plots without cover crops.
Field studies were conducted to determine critical period of weed interference in arracacha and tanier and data analysis is in progress. Field experiments are in progress to determine plant nutrient competition in sweet potato, weed management strategies in tanier and to evaluate efficacy and phytotoxicity of sethoxydium in arracacha.
Impacts
(N/A)
Publications
- LUGO, M. DE L., ACEVEDO, E., and LIU, L. C. 1998 Oxyfluorfen in `Alela' and `Estela' taniers. J. Agric. Univ. P.R. 82:227-229 (RN)
- LUGO, M. de L., ORENGO, E. y ACIN, N. 1998. Paraquat sethoxydim en apio. Annual Meeting of the Puerto Rican Society for Agricultural Sciences, 13 November 1998, Carolina, Puerto Rico.
- SEMIDAY, N., ACEVEDO, E., and FLORES, L. E. 1998. Weed management in dry beans in Puerto Rico. Annual Meeting of the Caribbean Food Crops Society. July 12-18, 1998. Montego Bay, Jamaica.
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Progress 01/01/97 to 12/01/97
Outputs
Seven field experiments were conducted to evaluate eight herbicides and a mulching practice in five tropical crops during the past year. In tanier, oxyfluorfen gave a better control of weeds than ametryn at the two rates tested (0.56 and 1.12 kg ai/ha). Oxyfluorfen at its higher rate resulted in a higher tuber yield than ametryn at its lower rate. Yield data on critical periods of weed interference in tanier are still pending. In arracacha, sethoxydim, applied either once or twice, gave good grass control. Paraquat applied either once or twice gave excellent weed control but caused 20% crop phytotoxicity with the second application. However, this paraquat treatment gave the highest tuber yield (16,452 kg/ha). In coffee, four native grasses and one introduced legume were evaluated as living mulches. Dalisgrass (Paspalum dilatatum) supressed the most weeds of all the treatments. The control treatment, consisting of glyphosate application at an interval of every three to
four months resulted in the highest soil loss of all treatments. In bean, imazethapyr was evaluated according to the methods of application (preplant incorporated, preemergence, and postemergence). Different application methods did not significantly affect the weed density and dry bean yield. In pigeon peas, imazethapyr was more selective than prometryn and metribuzin on the basis of the yields of five pigeon pea cultivars. Cortada was the cultivar most tolerant to all three herbicides.
Impacts
(N/A)
Publications
- LUGO, M. DE L. and ACEVEDO, E. 1997. Weed interference in tanier. Proceeding of the Caribbean Food Crop Society. San Juan, P.R.
- LUGO, M. DE L., ACEVEDO, E., LIU, L.C. and ACIN, N. 1997. Pre-emergentes en yautia. Proc. Soc. Puertoriquena de Ciencias
- LIU, L.C., ORENGO, E. and LUGO, M. DE L. 1997. Evaluation of clomazone in arracacha and cassava. J. Agric. Univ. P.R.
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Progress 01/01/96 to 12/30/96
Outputs
Nine field experiments were conducted to evaluate herbicide efficacy or weed interference in six crops. In peppers, an IR-4 protocol on the magnitude of residue of oxyfluorfen has been completed and submitted. In bean, bentazon (1.12 kg ai/ha) caused more injury than trifluralin and imazethapyr. However, there was no significant yield differences among different herbicide treatments. In pigeon peas, prometryn (4,48 kg ai/ha) and metribuzin (1.50 kg ai/ha) caused low to moderate injury to five pigeon pea cultivars three weeks after herbicide treatments. Imazethapyr (0.10 kg ai/ha), on the other hand, did not cause any injury to the five cultivars. In tanier, oxyfluorfen at 0.56 and 1.12 kg ai/ha gave 88% and 95% weed control, respectively, four weeks after herbicide application. Ametryn at 3.36 and 5.60 kg ai/ha provided 80 and 89% of weed control, respectively, in the same experiment. Yield data for these herbicide treatments are still pending. In arracacha, paraquat
at 0.56 and sethoxydim at 0.34 kg ai/ha produced 84% and 80% weed control, respectively, three weeks after herbicide application. A critical period of weed interference study on tanier has been continued into its second year. A new weed interference study on arracacha was initiated this year. In coffee, a living mulch experiment using four native grasses and one introduced legume was initiated. The preliminary data showed that pond peanut and carpet grass were higly promising.
Impacts
(N/A)
Publications
- LUGO, M. DE L., and SANTIAGO, L.R. 1996. Herbicide screening in cilantro and spiny coriander. J. Agric. Univ. P.R. 80 (1&2):73-75.
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Progress 01/01/95 to 12/30/95
Outputs
Fourteen field experiments were conducted to evaluate herbicide efficacy or weedcompetition in nine crops. In cabbage, clomazone (1.12 kg ai/ha) and oxyfluorfen (0.28 kg ai/ha) were equally effective for weed control when applied 5, 10 and 15 days before transplanting. Both herbicides produced yields similar to that of handweeded control. In peppers, oxyfluorfen gave 84% weed control and increased yield by 40%. In calabaza, weed control and yield did not improve by intercropping with cabbage, cowpeas and pigeon peas. Plant height and fresh pod yield was significantly increased when pigeon pea was treated with imazethapyr at 0.07 and 0.14 kg ai/ha rates. In tuber and root crops, the average clomazone treatment produced 64%, 70%, 107% and 108% of the handweeded control for yams, taniers, cassava and arracacha, respectively. In another yam experiment, imazethapyr (0.112 and 0.224 kg ai/ha) gave controlled weeds much better than lactofen (1.68 and 3.36 kg ai/ha) when both
were applied preemergence. However, the final tuber yield did not reflect the improved weed control by imazethapyr. In coffee, sulfosate (1.68 and 3.36 kg ai/ha) continued to give excellent weed control and produced good coffee berries equivalent to that of glyphosate treatment (2.24 kg/ha). An experiment on the critical period of weed competition in taniers was initiated this year. A regression analysis will be conducted to determine the effect of timing of weed removal on yield reduction of this tuber crop.
Impacts
(N/A)
Publications
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Progress 01/01/94 to 12/30/94
Outputs
Fifteen field experiments were conducted to evaluate herbicide performance in 11crops. In cabbage and calabaza experiments, clomazone (1.12 kg ai/ha) and oxyfluorfen (0.28 kg ai/ha) significantly decreased weed density. Both herbicides applied pre-plant produced same yields hand weeded control. In an onion experiment, pre-plant application of glyphosate (1.68 kg ai/ha) gave good control of purple nutsedge. Clomazone (1.68&3.36 kg ai/ha) gave good to excellent control of grasses and broadleaf weeds in yam, taniers, cassava and arracacha. Glyphosate at 2% gave excellent preemergence control of emerging weeds in yams and taniers. Sethoxydim (2%) provided good control of all grasses in taniers and cassava. In a herbicide screening experiment on taniers imazethapyr (0.14 kg ai/ha) gave the best weed control of the six herbicides. In an on-going coffee experiment, sulfosate (1.68 & 3.36 kg ai/ha) and glyphosate (2-24 kg ai/ha) continue to provide excellent weed control. The
mixture of fluazifop with oxyfluorfen effectively controlled broadleaf weeds in coffee but not in grasses. In coriander and spiny coriander experiments, oxyfluorfen (0.13 & 0.26 kg ai/ha) and sethoxydim (0.22 & 0.44 kg ai/ha) gave the best weed control and produced intermediate yields. In two pasture experiments, diuron (1.68 kg ai/ha) & 2,4-D (2.24 kg ai/ha) mixture and 2,4-D (2.24 kg ai/ba) alone gave the best control of weeds in stargrass and Bermuda grass (Tifton 85).
Impacts
(N/A)
Publications
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Progress 01/01/93 to 12/30/93
Outputs
Ten field experiments were conducted to evaluate herbicide performance in 11 crops. In cabbage, clomazone (1.12 & 2.24 kg ai/ha) and oxyfluorfen (0.28 & 0.56 kg ai/ha) as a preplant were found to be the outstanding treatments. The highest calabaza yield was obtained with a herbicide treatment consisting of clomazone (1.1,2 kg ai/ha, preemergence) followed by paraquat (0.56 kg ai/ha directed to the weeds). None of the three herbicides and their combinations tested effectively controlled purple nutsedge in onions. Neither oxyfluorfen nor lactofen plus fluazifop-P provided sufficient weed control and yield improvement in peppers. In yams (Dioscorea rotundata), imazethapyr (0.112 & 0.224 kg ai/ha) gave the best preemergence control of weeds, but did not improve the tuber yield. Linuron (3.36 & 6.72 kg ai/ha) provided only fair preemergence control of weeds in tanier and cassava. Both sulfosate (4.68 L/ha) and glyphosate (4.68 L/ha) gave excellent post-emergence control of
all weeds in coffee. In pineapple, fruit samples of quizalofop (0.448 & 3.58 kg ai/ha) treated pineapple plants were collected and sent to an IR-4 Regional Laboratory for residue analysis. In coriander (Coriandrum sativum L.), oxyfluorfen at 0.26 kg ai/ha preemergence, and sethoxydim at 0.44 kg ai/ha postemergence, gave good to excellent control of all grasses. Coriander was highly tolerant to all five herbicides tested.
Impacts
(N/A)
Publications
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Progress 01/01/92 to 12/30/92
Outputs
Eight field tests were conducted to evaluate ten herbicides, and a plastic mulching treat- ment for weed control in eight crops. In pumpkin, the integrated plastic mulching + paraquat treatment did not differ significantly in yield (P = 0.05) from oxyfluorfen (0.28, 0.56 & 1.12 kg ai/ha) or fluazifop (0.47 & 0.94 kg ai/ha) + paraquat (0.56 kg ai/ha). In sweet cherry peppers, the integrated plastic mulching + paraquat (0.56 kg ai/ha) significantly outyielded preplant and postemergence applications of either glyphosate (1 and 2%) or paraquat (0.56 kg ai/ha) treatments. In onions, the highest yield was obtained from the handweeded control. This was followed by fluazifop (0.47 kg ai/ha) + oxyfluorfen (0.28 kg ai/ha) mixture as an early postemergence treatment. The inclusion of bentazon (0.84 kg ai/ha) as a follow-up treatment to the above mixture did not increase yield but showed an increase in crop injury. In yams, linuron (3.36 kg ai/ha) gave only fair weed control.
Weed control was improved at a higher rate (6.72 kg ai/ha) but with slight crop injury that did not affect significantly the tuber yield. In taniers and cassava, linuron at two rates as indicated in yams, gave satisfactory control of weeds. In pineapple, quizalofop at 0.90 & 3.60 kg ai/ha have excellent control of weeds with yield data pending. In beans, the highest yield was obtained with alachor (5.32 kg ai/ha) + mechanical cultivation. In another trial, the handweeded control show the highest yield with sethoxydim (0.56 kg ai/ha) alone yielding second.
Impacts
(N/A)
Publications
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Progress 01/01/91 to 12/30/91
Outputs
Nine field experiments were conducted to evaluate 10 herbicides in 7 crops. A nursery and a field experiment in coffee were completed where fluazifop-p at 0.28 and 1.12 kg ai/ha and quizalofop at 0.224 and 0.896 kg ai/ha, were applied as postemergence sprays for control of grasses. Slightly better control was obtained with quizalofop than with fluazifop at corresponding rates in both nursery and field trials. Fluazifop-p, at 0.28 and 0.56 kg ai/ha and quizalofop at 0.224 and 0.448, were similarly evaluated in pineapple trials. Both herbicides at indicated rates gave excellent control of grasses and caused no apparent crop injury to pine-apple plants. Clomazone at 1.12 kg ai/ha gave best weed control in a direct-seeded pepper experiment. Oxyfluorfen at 0.28 kg ai/ha / fluazifop-p at 0.47 kg ai/ha as an early postemergent in sequential applications with oxyfluorfen alone at 0.28 kg ai/ha gave best weed control and highest yield in onions. The combination of plastic
mulching on the row and directed paraquat sprays at 0.47 kg ai/ha between rows provided the best weed control and resulted in highest yields in sweet cherry peppers. In green beans, fluazifop-p at 0.56 kg ai/ha effectively controlled perennial grasses up to 56 days after planting. Trifluralin at 0.88 kg ai/ha in sequential applications with fluazifop-p at 0.59 kg ai/ha was the best combination treatment on beans. Neither adjuvants nor additives significantly enhanced the postemergence activity of glyphosate at 0.5, 1.0 and 2.
Impacts
(N/A)
Publications
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Progress 01/01/90 to 12/30/90
Outputs
Fifteen field experiments were conducted to evaluate 20 herbicides in nine crops. In vegetable crops, clomazone at 2.24 kg ai/ha in sequential applications with paraquat directed at 0.56 kg ai/ha provided the best weed control and highest yield in peppers, sweet cherry peppers and pumpkins. Oxyfluorfen at 0.42 and 0.84 kg ai/ha, on the other hand, was highly phytotoxic and resulted in the lowest yield. In green beans, fluazifop at 0.77 and sethoxydim at 0.60 kg ai/ha were moderately effective against annual and perennial grasses. Sethoxydim and trifluralin treatments yielded more than 370 kg/ha of green-shelled beans. In pigeonpeas, imazethapyr at 0.056 to 0.224 kg ai/ha was again evaluated this year and continued showing promise as pre or early postemergence. Glyphosate and fluazifop were also evaluated in separate experiments for postemergence weeds. Ametryn at 4.48 kg ai/ha, imazethapyr at 0.224 kg ai/ha and linuron at 2.80 kg ai/ha followed by fluazifop at
0.42 kg ai/ha also provided good to excellent weed control in yams. Registration trials of ametryn and glyphosate in yams, taniers and cassava are in progress. Ametryn at 4.48 kg ai/ha followed by paraquat directed at 0.56 kg ai/ha provided excellent weed control in taniers; yield data are pending. Another fluazifop experiment on taniers is in progress. In forage grass trials, tebuthiuron at 336 kg ai/ha gave excellent control of weeds in Guinea grass pasture but with severe crop injury.
Impacts
(N/A)
Publications
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Progress 01/01/89 to 12/30/89
Outputs
Field experiments were conducted in 1989 to evaluate 12 herbicides in nine crops. In sugarcane, the handweeded check (43.6 T/A) outyielded all plots receiving herbicide treatments. Pendimethalin at 4.48 kg ai/ha also gave a high yield whereas hexazinone at 4.48 kg ai/ha and imazethapyr at 1.17 l/ha resulted in the lowest yields. No significant differences in number and weight of plantains were measured when paraquat was applied at 2.34 l/ha and glyphosate at 1% either under tilled on non-tilled conditions. High yields of non-bell peppers were obtained when clomazone at 1.68 or 3.36 kg ai/ha was applied. Fluazifop at 0.42 kg ai/ha + bentazon at 2.34 l/ha also resulted in a high pepper yield. Yields of sweet cherry pepper treated with clomazone at 3.36 kg ai/ha were high. Pumpkin treated with clomazone at 2.24 kg ai/ha outyielded all other herbicide treatments. In pigeon peas, the hand-weeded check was the highest yielder, followed by imazethapyr at 0.056 and 0.112 kg
ai/ha as a preplant or postemergence treatment. Weed control using imazethapyr at 0.448 kg ai/ha and clomazone at 3.36 kg ai/ha, respectively, led to high yields. Both imazethapyr and clomazone gave good weed control in tanier.
Impacts
(N/A)
Publications
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Progress 01/01/88 to 12/30/88
Outputs
A series of field experiments were conducted to evaluate herbicides in several crops during 1987. In sugarcane, terbutryn at 6.72 kg ai/ha outyielded the unweeded control and asulam at 9.35 1/ha treatment in terms of can tonnage and sugar production. In plantains, glyphosate at 1% gave better sustained weed control than paraquat at 2.34 1/ha under both till and no-till conditions. Good to excellent weed control in pigeon peas was obtained with pre-plant incorporated teatment of imazethapyr at rates ranging from 0.56 to 0.224 kg ai/ha. In onions, oxyfluorfen at 0.14 kg ai/ha + fluazifop at 0.25 kg ai/ha, and oxyfluorfen + sethoxydium at 0.25 kg ai/ha outyielded all other herbicide treatments. In peppers, paraquat at 0.56 kg ai/ha as a pre-plant treatment followed either by oxyfluorfen at 0.14 kg ai/ha or by fluazifop at 0.25 kg ai/ha provided excellent weed control and high commercial yield. Tebuthiuron at 3.36 kg ai/ha provided the best weed control of the four
preemergence herbicides tested in a stargrass pasture. In another trial, excellent control of climbing mimosa, a noxious weed in local pasture, was obtained with recommended rates of pictoram and 2, 4-D + dicamba. Efficacy and residue data of paraquat gathered during past few years have culminated in the recent registration of the herbicide in for taniers, yams and cassava. Similarly, the registration of fluazifop for yams has also been achieved.
Impacts
(N/A)
Publications
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Progress 01/01/87 to 12/30/87
Outputs
Several field trials were conducted to evaluate herbicides and other weed control methods in different crops during 1986. In sugarcane, terbutryn at 10.7 kg ai/ha, and pendimethalin at 0.89 kg ai/ha imazapry at 1.125 kg ai/ha gave excellent grass control and produced the highest cane tonnage and sugar yield in separate trials. In pigeon peas, fluazifop-butyl at 0.42 to 1.68 kg ai/ha, oxyfluorfen at 0.33 kg ai/ha and metribuzin at 0.56 kg ai/ha provided excellent weed control. In yams, sequential application of ametryn at 4.48 kg ai/ha and fluazifop-butyl at 0.56 kg ai/ha produced the highest tuber yield (6,320 kg/ha). In rice, sequential application of propanil at 3.36 kg ai/ha and cinmethylin at 50 g/ha gave excellent weed control and produced the highest grain yield (3,165 kg/ha). In onions, postemergence application of oxyfluorfen at 0.125 kg ai/ha fluazifop-P at 0.42 kg ai/ha provided effective weed control and produced high yield. In peppers, napropamide at
2.24 kg ai/ha handweedings produced high yields. In pumpkin, handweeding postemergence application of metolachor at 3.36 kg ai/ha gave best weed control in one trial, the highest yield was obtained from metolachor at 3.36 kg ai/ha rotavator handweeding treatment in another trial. Chloramben at 2.24 kg ai/ha provided poor weed control and produced low yield in the same trial.
Impacts
(N/A)
Publications
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Progress 01/01/86 to 12/30/86
Outputs
Terbutryn at 2.86 and 5.35 kg ai/ha applied postemergence effectively controlledproblem weeds in sugarcane with no visible phytotoxic effects. Pendimethalin and imidazolinone combination provided better weed control in sugarcane than that achieved individually. The highest onion yield was obtained with the integration of DCPA at 11.2 kg/ai ha as a preemergence, oxyfluorfen at 0.56 kg ai/ha as an early postemergence and hand weeding. Preliminary evaluation of sethoxydium, fluazifop-butyl and DPX-Y6202 showed no detrimental effect of these herbicides on yields of pumpkin, cucumber and watermelon. The highest pumpkin yield was obtained with the integration of chloramben at 3.0 kg ai/ha, mechanical cultivation and hand weeding. Fluazifop-butyl at 0.42, 0.84 and 1.68 kg ai/ha gave excellent control of grasses in pigeon pea and produced good pod yields. The same herbicide at 0.28 and 0.56 kg ai/ha provided excellent grass control in yams. Oxyfluorfen in sequential
applications was more effective against grassy weeds than broadleaf weeds in pigeon pea. Metribuzin and glyphosate combination greatly improved weed control and pigeon pea yield. Oxyfluorfen at 1.5 1/ha rate produced rice yield as high as the standard thiobencarb herbicide in a field trial at Arecibo. Directed application of glyphosate at 2.0 and 4.0 kg ai/ha provided better control of problem weeds in pineapple than paraquat at 0.56 kg ai/ha. However, their difference in weed control did not reflect in pineapple yield.
Impacts
(N/A)
Publications
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Progress 01/01/85 to 12/30/85
Outputs
Three experiments on integrated weed management on watermelon, eggplant and pumpkin were conducted at Lajas and Juana Diaz. Integration of DCPA into eggplant or watermelon management with two hand weedings increased crop yields. The critical period of weed competition in Rosita eggplant was established at 28 days after transplanting and for Borinquen pumpkin at 21 and 35 days at Juana Diaz and Lajas, respectively. Excellent yields of pigeon peas were obtained with oxyfluorfen (0.33, 0.66 and 1.32 kg ai/ha) preemergence and over the top. Glyphosate directed sprays (0.41, 0.82 and 1.64% v/v) did not show significant differences on yield as compared to check treatment. Fluazifopbutyl provided excellent grass weed control seventeen weeks after treatment. Highest edible root yield was obtained with 3 applications of paraquat at 2.34 1/ha rate to cassava at Isabela. Oxyfluorfen at 1.5 1/ha rate is being evaluated for preemergence weed control on rice at Arecibo.
Excellent weed control with no phytotoxic effects, similar to the standard thiobencarb herbicide, were noted in rice; yield data for this trial are pending. A metribuzin experiment on pineapple will be harvested on January 1986 for crop yield and residue analysis. Glyphosate and paraquat are under evaluation for control of Brachiaria plantaginea, Paspalum urvillei and Digitaria sanguinalis.
Impacts
(N/A)
Publications
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Progress 01/01/84 to 12/30/84
Outputs
The grass herbicides sethoxydim (Poast), fluazifop-butyl (Fusilade), and DPX-Y6202 (Assure) were evaluated in a primary screening on 9 vegetables and pigeon pea. Good weed control of grass weeds was obtained with no toxic effects to broadleaf crops. Sweetcorn was affected. Secondary replicated trials with cabbage and eggplant transplants were conducted. Herbicides controlled weeds effectively and did not affect eggplant nor cabbage, which produced acceptable yields. Oxyfluorfen was toxic to pigeon pea in 2 trials. It reduced crop stand and plant growth as preemergence and postemergence treatment. The highest fruit yield of plantain was obtained with 1% SC-0224. Fusilade (0.28 kg ai/ha) in another experiment also promoted excellent weed control and yield. Oxyfluorfen (1 1/ha) preemergence was the best treatment in rice. A trial with the herbicides hexazinone, bromacil, diuron, metribuzin and mixtures was established in August 1984 to control weeds in pineapple.
Hexazinone, bromacil, metribuzin, and Krovar were the best treatments in a December evaluation. In a greenhouse test, a new weed on pineapple fields (Brachiaria plantaginea) was inhibited by bromacil, ametryn, and metribuzin.
Impacts
(N/A)
Publications
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Progress 01/01/83 to 12/30/83
Outputs
Round up at 1, 2 and 4% (v/v) was evaluated as directed spray on transplanted tomato and sweet pepper. Good weed control was obtained with 2 postemergence applications. Tomato yield was superior in hand weeded plots, but no significant differences in yields were observed in sweet pepper in 4 pickings. Ametryn preemergence, 4.48 kg a.i/ha plus 3 directed Paraquat sprays, 2.34 l/ha promoted the best yields. Ametryn preemergence plus Paraquat postemergence as with tanier gave the best results in yams. In Metribuzin-treated pineapple plots, yields were similar to those the standard herbicide mixture (Ametryn + Atrazine). Paraquat was less effective than Glyphosate to control weeds in citrons. Glyphosate controlled effectively Setaria palmifolia, Commelina diffusa and Ipomoea tiliacea in 3 replications of 45-day intervals for 6 months. Excellent weed control was achieved with Glyphosphate applied every 70 days in non-bearing acerola trees. In bearing trees, weed
control this year was less efficient with Paraquat and Dalapon. The weeded rice check was the highest grain yielder followed by Propanil at 3.36 kg ai/ha. Preemergence Bifonox plus Bentazon postemergence ranked third. Oxyfluorfen at 6 l/ha ranked second to the weeded check plots in number and weight of plantains.
Impacts
(N/A)
Publications
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Progress 01/01/82 to 12/30/82
Outputs
Metribuzin (Sencor 50W) at 4.48 kg.ai./ha. showed good postemergence weed control and good cane and sugar tonnage at Lajas and Gurabo. Weedmaster, dicamba, 2,4-D and asulam were evaluated in sugarcane at Lajas. Treated plots yielded similar results as cultivated plots. Pumpkin and pigeon pea yields were higher in weeded plots and excellent broadleaf control was attained at Lajas. Glyphosate (1%) preemergence followed by a wiper 5% application to taniers and yams was best herbicide treatment in Corozal and Isabela. Butachlor plus propanil showed good weed control in rice at Vega Baja. West Indian cherries treated with paraquat and dalapon were collected for residue analyses at Naguabo. Three applications and 7 concentrations of glyphosate were applied to infested pastures at Barceloneta, Camuy, and Gurabo, showing complete eradications at concentrations over 20%. Application methods showed no statistical differences. Oxyfluorfen and simazine at 2 kg./ha. were
found best for the pre- and post-emergence control of weeds in Spanish Bayonet and Rainbow tree ornamentals.
Impacts
(N/A)
Publications
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Progress 01/01/81 to 12/30/81
Outputs
Three experiments were harvested and the yields recorded. Cane and sugar tonnagewith Metribuzin at 4.48 kg pre - 2.24 kg ai/ha postemergence was higher at Lajas and Gurabo. Asulam 2.9 kg ai/ha postemergence following a preemergence application of Metribuzin was the best herbicide treatment in yields at Lajas. Paraquat was evaluated in tomatoes and sweet peppers at Lajas. Cyanazine was phytotoxic to sweet corn; other preemergence herbicides gave good control and crop yields. In taniers and yams, Paraquat was the best herbicide regarding tuber yields either alone or combined with Ametryn preemergence. Glyphosate was also promising for use in yams. Ametryn pre + Glyphosate postemergence was good for cassava production. In sweet potatoes, Metribuzin + Alachlor produced the highest tuber yield. Hexazinone and Bromacil alone or combined gave excellent preemergence control of weeds in pineapple. Paraquat was a good leaf desiccant. Glyphosate was excellent in weed
control in a 6-month-old plantation. Oxyfluorfen (Goal) was effective and was not toxic in coffee and Napropamide was inferior. Glyphosate directed to weeds outyielded Diuron in 2 plantain experiments. Molinate + Propanil controlled weeds effectively in rice and produced the highest yields in experimental and semicommercial rice plots. On bearing acerola trees, Paraquat controlled weeds effectively when applied at 1- to 2-mo intervals.
Impacts
(N/A)
Publications
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Progress 01/01/80 to 12/30/80
Outputs
Pigeon peas: Three herbicide experiments were established during 1980. Paraquat was evaluated for a 24(c) registration. New chemicals evaluated included propachlor, alachlor, pendimethalin and cyanazine. Sugarcane: Three experiments are underway evaluating metribuzin rates, asulam and the herbicides commonly used for cane production. Vegetable crops: Unregistered oxadiazon (onions), trifluralin (beans), chloramben (pumpkins), metribuzin (tomatoes), diphenamid (peppers), and DCPA (watermelons and cucumbers) were the best herbicide treatments. Root crops: Paraquat (taniers), ametryn and prometryn (cassava), ametryn/paraquat (yams), alachlor-metribuzin (sweet potatoes) produced the highest yields and the best weed control. Pineapples: Both paraquat and glyphosate were excellent in controlling weeds and increasing crop yields. Paraquat was also an effective plant desiccant for destroying ratoons. Rice: Propanil alone and in mixtures is still the best treatment.
Bananas and plantains: New trials were begun to substitute those damaged by a hurricane. Coffee: Glyphosate was best treatment. Acerola: Metribuzin was toxic to the crop. Other herbicides provided control for only 45 days. Forages: Glyphosate plus simazine preemergent produced the best control and the higher crop yields.
Impacts
(N/A)
Publications
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Progress 01/01/79 to 12/30/79
Outputs
Trifluralin E DCPA (preplant) and Diphenamid (preemg) were the best for tomato, cabbage and pepper. Chloramben and Alachlor were the best for pumpkins and dry beans. Sencor is an excellent pre and post weed controller in sugarcane; Ametryne a fair one. Prometryne reduced pigeon pea yield. Glyphosate controlled weeds in drainage canals. Fewer applications of Glyphosate than of Gramoxone and Dowpon controlled the weeds in coffee. Plantains yielded more under Glyphosate than Paraquat at similar rates. Glyphosate controlled weeds well although causing injuries. Intercropping coffee and plantains reduced the weeds and the number of applications required. Additional control was obtained with Round-up or Gramoxone. Cyanazine applications caused fair tuber yields (second to the hand weeding) in taniers; DCPA and Oryzalin caused poor yields. Ametryne was an effective preemg for taniers, but at high levels caused injuries. Paraquat is a promising postem. Ametryne and
Prometryne were toxic to cassava. Paraquat and Round-up were good postem, but toxic to young cassava (less toxic for older plants). Butachlor, Oxidiazon and Propanil controlled weeds well in rice. Butachlor caused toxic effects. Propanil-Oxidiazon was the best combination. Round-Up controlled the growth of Venezuela grass tops (Paspalum fasciculatum), but induced stolen growth and stand renewal. Applying 2 and 4 kg/ha of Round-Up, 2 to 3X/mo. controlled the renewal. Round-Up and Simazine controlled weeds well when establishing Stargrass pastures.
Impacts
(N/A)
Publications
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Progress 01/01/78 to 12/30/78
Outputs
Minimum tillage and preemergence herbicides were studied on corn and pepper. Oncorn, Simazine was best in weed control, followed by Atrazine and Atrizine plus Linuron. Trifluralin, Nitralin plus DCPA incorporated to the soil gave excellent control in direct seeded peppers. Same herbicides were effective for transplanted peppers. Diphenamid provided good preemergence control in taniers. Glyphosate, Ametryne and Linuron were also effective. Fluometuron although toxic to tanier, provided good control in cassava. Linuron was toxic while Cyanazine was ineffective in cassava. Postemergence control in plantains was excellent with Glyphosate but not with Paraquat. Gramoxone at 0.95 1/ha prevented weed growth in coffee. Dowpon controlled narrowleaf weeds, but not broadleaves. Round-Up resulted in good control in coffee, with no phytotoxicity. Mortality of coffee was high and yield low when Karmex was mixed with Gramoxone or Dowpon. Weed incidence and number of
herbicide applications can be reduced by intercropping plantain and coffee. Less labor is required when plantain population/ha increased. Good control in pigeon pea occurred with all Prometryn rates. Phytotoxicity was observed only at 4X rate. All concentrations of Round-Up were effective against Venezuela grass. Medium and high rates translocated into underground parts. With 2 kg/ha grass sprouted and reestablished. Atrazine and Simazine controlled weeds in newly planted centipede grass for 2 months.
Impacts
(N/A)
Publications
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Progress 01/01/77 to 12/30/77
Outputs
Data indicates that 2.5 1/ha of Paraquat monthly gave excellent weed control in coffee at Adjuntas. Dowpon at 5.6 kg/ha every 12 weeks or 11.2 kg/ha every 16 weeks controlled gramineous but not broadleafed weeds. Round-up provided good weed control without toxic effects. Karmex was very toxic to coffee. Planting coffee under plantain, also at Adjuntas, reduced weeds and number of herbicide applications. Round-up gave better weed control than Paraquat in plantain at Corozal, at corresponding rates. In another plantain experiment at Corozal, yields were equal to or higher than in the hand-weeded plots under all herbicide treatments; highest yields were obtained under Ametryne & Diuron & lowest under Dowpon. Paraquat resulted the best weed controller. The best herbicide for weed control in taniers at Isabela was Prometryne. Idem in yams and cassava. Diruon was toxic to cassava. Metribuzin at 0.85 kg/ha produced pigeon pea yields similar to the hand-weeded plots.
Prometryne ranked second to Metribuzin in this respect. Chloromben at 6.7 kg/ha was toxic to pigeon peas. Pre- and postemergent herbicide evaluation in 24 sugarcane varieties showed that best preemergent treatment was Metribuzin (2.24, 3.36 kg/ha) followed by Velpar (2.24) and Terbacil. Weedmaster, Banvel & Velpar were the best postemergent treatments.
Impacts
(N/A)
Publications
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Progress 01/01/76 to 12/30/76
Outputs
The most promising herbicides for the control of broadleafed weeds in centipede turf were 3-D-Weedone, Super-D-Weedone, Tordon 101 and Banvel D + 2,4-D, Dal-E-Rad was toxic at all concentrations. Paraquat at 2 pt/A applied monthly provided excellent weed control in young sun-grown coffee. Dalapon at 5#/A every 12 wk or at 10#/A every 16 wk controlled grassy weeds. Karmex at 2#/A applied at either 12 or 16 wk was highly toxic. The advantage of using closely spaced plantains to provide shade to young coffee was further demonstrated. It favored the growth of coffee and controlled weeds, thus reducing the need for herbicide applications. Unregistered preemerge herbicides were evaluated in pigeon pea, pumpkin, water melon and Tandew melon. Positive results were obtained with 1 and 2#/A Metribuzin in pigeon pea. Registered chloramben was thebest herbicide for control of weeds in pumpkin. Registered NPA was of short duration in the soil. Un- registered Metribuzin EC &
WP at 0.75# ai/A gave bestresults in pre and postemergence applications. Buban-37 at 4#/A provided best weed control in Walker tomato at Fortuna. Dacthal was superior to Buban-37, H-22234 and CGA24705 in Market Prize cabbage. Paraquat at 2 pts/A was best postherbicide for plantain. Hand hoeing, hoeing + hilling-up and Diphenamid at 6#/Apost + hilling were the best treatments for weed control in field grown tobacco.Venezuela grass was effectively
Impacts
(N/A)
Publications
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Progress 01/01/75 to 12/30/75
Outputs
Glyphosate, Velpar, and RH-2915 in postemergent (post) applications at 3.1, 4.0 and 4.0 kg/ha, respectively, were the best herbicides for controlling Paspalum fasciculatum. Positive results were obtained with unregistered postemergent herbicides in pigeon pea, eggplant, pumpkin, bean, pepper, sweet corn, watermelon, tomato, sunflower, cucumber, and cantaloupe. One-hundred tomato cultivars showed varying sensitivity to pre and post. Ametryne pre at 4# a.i. compared favorably in weed control with hand weeded tanniers or when combined with post herbicide applications. Pre applications of ametryne at 4# combined with post applications of dalapon, ametryne, prometryne or glyphosate reduced yield of yam significantly. Pre and post herbicide applications to second ratooned cane provided best weed control, followed by mechanical cultivation. Two or more cultivations provided only 60% control. Paraquat at 2 pts, fortnightly, provided excellent weed control in coffee.
Dalapon at 5 every 12 weeks or 10# every 16 weeks also gave good weed control. Diuron + dalapon or paraquat at 12-week intervals gave fair control; the treatment was ineffective at 16 weeks. Trial with coffee planted under banana showed that the closer the bananas were planted the lower the weed incidence and the number of herbicide applications required. Paraquat at 2 pts every 30 days gave effective weed control in citrus. In this respect, dalapon at 5# was as effecti as at 10#. Bromacil, at 3#, was effective for a 4-month period.
Impacts
(N/A)
Publications
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Progress 01/01/74 to 12/30/74
Outputs
Paspalum fasciculatum was effectively controlled by Round-up 3-6 lbs/A (#) & Dowpon 10#. Best results were obtained with preemergent and postemergent (pre &post) herbicides in 12 crops, as follows: Pre - pigeon pea, Metribuzin at .5# & Chloramben at 3#; eggplant, Bifenox at 1.5#; pepper, Hercules 22234 at 3#; tomato, Metribuzin at 1#; okra, Gulf S-6796 at 4#; corn, Bifenox at 1.5#; lettuce, Pronomide at 3#. Post - tomato, Metribuzin at .75#, following Diphenamid at 6#; cabbage, Nitrofen at 3#. Dalapon 3# + Karmex 2# a.i. gave goodpost weed control in tanier. Ametryne post 4# (a.i.) was very effective in yam.At Isabela & Fortuna there were no differences in cwts sugar/A between hand weeded & Karmex 8#/A in fall planted cane. Weed control (42 days) was attained also by Karmex at 8#. In ratoon cane at Isabela, Lajas and Fortuna, Sencor gavethe best weed control. At Lajas hand weeding was superior to Sencor 2# in % sucrose. Ametryne 4# was superior to Sencor in cwts
sugar/A at Isabela and % sucrose at Lajas. Karmex 4 & 8# and mixture of Dowpon 3# + Karmex 2# gave good post weed control in ratoon cane. There were no differences between Ametryne 8#, Sencor 2, 4 & 8# and Karmex & Prometryne 4 & 8# in control of weeds in plantains. Ametryne & Prometryne were the least injurious. Karmex 2# + Gramoxone 2 pts was promising in coffee & citrus. Diphenamid 5# pre or Amiben pre or post 2# gave the best weed control in tobacco. Picloram + 2,4-D and Dicamba + 2,4-D controlled weeds effectively in Pangolagrass.
Impacts
(N/A)
Publications
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Progress 01/01/73 to 12/30/73
Outputs
Krobar I at 4 lbs/A kept pineapples clean for 8 months. Glyphosate gave excellent postemergence control of weeds in coffee in the greenhouse. Sencor and Karmex at 2 lbs/A postemergent controlled weeds in plantains. Diphenamid at10 lbs and Diphenamid at 4 lbs + Amiben at 6 lbs/A gave best weed control in sweet potatoes. Ametryne at 4 lbs preemergent and Karmex at 4 and 8 lbs/A postemergent gave a 3 month control in yams. Dowpon at 5 lbs every 3 months controlled grasses in coffee and citrus; and Karmex at 2 lbs + Gramoxone at 4 pts in mature coffee. Sencor at either 2, 4 or 8 lbs/A gave best weed control in spring and fall planted and ratoon cane. Sinbar was also good. Amiben, 3.0 lbs best preemerge in pigeon pea. Treflan, 1.0 lb best preemerge in okra. Dacthal, 10.5 lbs as preemerge followed by Tok E-25, 3.0 lbs as postemerge gave best results in onions. Sencor, 0.5 lb as preemerge followed by Sencor, 0.5 lb as postemerge was best in tomato. Lasso, 4.0 lbs as
preemerge followed by Ramrod 65, 6.0 lbs as postemerge and Sinox Pe, 4.5 lbs (when used as postemerge only) preceded by no preemerge treatment, gave excellent results in sweet corn. Dacthal, 10.5 lbs best as preemerge in transplant eggplant. Dacthal, 10.5 lbs still best preemerge in beans and cabbage. Analap still best preemerge in cantaloupe, cucumber and watermelon. In tobacco, both Diphenamid at 5 lbs/A andAmiben 2 lbs/A gave good control of weeds. Nevertheless, the quality of tobaccofrom plots with Amiben was lower by 12% than that from plots with Diphenamid.
Impacts
(N/A)
Publications
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Progress 01/01/71 to 12/30/71
Outputs
Herbicides were tested on rice, coffee, sugarcane and vegetables. The most promising herbicide for preemergence control of weeds in rice was Bas 3512H. Insugarcane, Asulam was effective against grassy weeds. Actryl D showed the opposite effect. Best results were obtained when both were combined in a singleapplication. Bay 94337 was outstanding against grassy and broadleafed weeds. Cyperus rotundus L. and Cynodon dactylon L. were controlled by Bay 94337. It also was very good as a pre-emergent for coffee, but Linuron at 4 and 8#/A was best. Dowpon at 5 or 10#/A and Gramoxone alone or in combination with Karmex orAmetryne were the best post-emergence herbicides. Dowpon was very effective against malojillo and gramalote grasses. The most effective herbicide for controlling prevalent weeds of our pineapple region was Hyvar X when applied either alone or in combination with Karmex or Ametryne. Hyvar can extend the weed control period from 3 to over 7 months.
Prometryne and chloramben (3, 6#/A) were outstanding in weed control on pigeon peas; chloramben (4, 8#/A) on pumpkin; and diphenamid (5, 10#/A) on peppers and (5, 10#/A) on tomatoes. Dacthal (DCPA) gave excellent results as a pre-emergent in green beans, cabbage and sweet corn. Sweet potato plots treated with combinations of Diphenamid and Dacthal or Amiben significantly outyielded untreated plots. Dalapon at 6 and 10#/A or in combination with TCA (Dowpon C) gave excellent initial kill of Para-grass. Amitrole-T at 5#/A was nearly as effective as Dalapon.
Impacts
(N/A)
Publications
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Progress 01/01/70 to 12/30/70
Outputs
Vegadex affected the germination of pepper, cabbage, tomato and eggplant. It was also injurious to developing plants. Randox was next to Vegadex in this respect. Sugarcane variety P. R. 61-53 was found to be susceptible to Karmex and Ametryne. Atrazine was found to be safe for sweet corn even at rates of 8 lbs./A. An experiment for the evaluation of Sinbar and Karmex established at Fortuna will be harvested during the 1970 harvest season. Data obtained this year in a Karmex-Sinbar combination experiment at Isabela were very erratic, duepossibly to heavy rainfall. This experiment will be repeated. A plantain experiment established at Corozal is being harvested. Another experiment was established at this same Station. Ametryne was applied after planting, followedby postemergence applications of Gramoxone. Plots of sweet potatoes were treated preemergently with Diphenamid at various rates in combination with Dacthal or Amiben and show promising results.
Experiments to evaluate registered preemergent herbicides on various vegetable crops were established inOctober and November, l970. Effect of herbicides on weeds and crops is being studied. Data on residues are also being collected. With tobacco a new trial was established in Gurabo to test Tillam, Balan and Diphenamid at various rates.With coffee two experiments were initiated at the Adjuntas Substation. To date the best treatments are Linuron a preemergent at 4 and 8 lbs./A and Dowpon as a postemergent at 5 and l0 lbs./A.
Impacts
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Progress 01/01/69 to 12/30/69
Outputs
Various combinations of Sinbar and Ametryne were applied preemergently to plots of P.R.980 infested with Bermuda grass, nutgrass and other weeds. Production of cane and sugar per acre, as well as, sucrose content was very high for all treatments. This indicates that there were, apparently, no ill effects from such treatments upon the growth and quality of the crop. In fact, there were nostatistical differences between treatments except in the case of one treatment, Sinbar 2 lb/A = Ametryne 3 lb/A. Sugarcane plots treated with this herbicide combination yielded significantly more sugar than the rest of the plots, that is, 177 hundredweights against 137, 147, 144, 150, 141, and 163 hundred-weights for the other treatments. In two trials carried out at the Fortuna Substation, Sinbar applied at rates of 1, 2, 3 and 4 lb/A alone or combined with Karmex and Ametryne had no deleterious effects on Bermuda grass and nutgrass.
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Progress 01/01/68 to 12/30/68
Outputs
Three experiments were established to evaluate the efficiency of various herbicides. The herbicides and concentrations respectively used were as follows: (1) Ametryne, Cotoran, Karmex, Atrazine, and Prometryne at 1, 2, 4, 8,16, 32 lb., Synbar at 1/4, 1/2, 1, 2, 4 lb./A. (2) Karmex, Ametryne at 4, 8 and16 lb., Synbar 1, 2, 3 lb./A. (3) Synbar 1 or 2 lb. combined with either 1, 2, 3 or 4 lb./A. of Ametryne. Ametryne, Diuron, and Synbar were the most effectiveherbicides from the standpoint of weed control. Synbar, Diuron, and Cotoran were toxic to sugarcane at the highest concentrations used. Sugarcane variety P.R. 1117 seemed to more susceptible to Synbar and Diuron than the P.R. 1085 variety. Synbar was very effective against Bermuda and nutgrass. These two weed species actually constitute the two most pressing weed problems in our sugarcane fields. Synbar-Ametryne combinations were found to be very effective for the suppression of Bermuda and nutgrass as well
as other weeds in P.R. 980 experimental plots.
Impacts
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Progress 01/01/67 to 12/30/67
Outputs
The two experiments established in 1964 at the Isabela and Lajas Substations arestill underway. The first ratoon crop was harvested by the middle of the current year's sugarcane harvest season. Data were taken on the weed controlling power of the different herbicidal treatments as well as on the effect of these, upon the yield of cane, sugar percent yield and sugar produced by the various cane varieties included in the above mentioned experiments. Datawere tabulated and are being analyzed statistically.
Impacts
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