Performing Department
(N/A)
Non Technical Summary
Grapes are the highest value fruit crop in the U.S valued at over $6.5 billion dollars. Vineyards are challenged by a variety of diseases and insect pest, including spotted lanternfly (SLF). SLF feeding is detrimental to grapevines causing yield losses of up to 90%, along with a reduction in wine quality, vine decline and death. These insects were accidentally introduced to Pennsylvania in 2014 and have spread to 13 additional States posing a threat to the U.S. grape and wine industry. Currently, chemical pesticides are the most common strategy for controlling SLF populations. Grape growers have reported an increased use of pesticide sprays in their vineyards that has considerably augmented their production costs and reduced their profit. Grape growers are aware of the importance of controlling SLF in their vineyards, but they are uncertain on when to apply control tactics. The goal of this proposal is to develop action thresholds to help guide growers on the appropriate SLF densities (number of insects per plant) that need to be targeted to avoid economic loss. Economic thresholds are the basis of insect pest management programs, and their use leads to a more efficient use of pesticides, reduction of environmental and human health risks, higher economic benefits to growers, and reduction of pest populations. Field-established grapevines will be enclosed in mesh cages and infested with diferent numbers of SLF individuals (from 0 to ~320). At the end of the growing season, the vines will be harvested and weighed to determine yield. Additionally, several grapes from each vine will be used for winemaking. The relationship between the number of SLF per vine and the resulting yield and wine quality will be assessed with appropriate statistical methods. This information will help determine the number of SLF individuals per vine that causes yield or wine quality loss. These data along with data on SLF management costs obtained from grape growers with previous SLF infestations will be used to calculate action thresholds for this insect. Action thresholds are the basis of insect pest management programs, they help guide growers on the appropriate timing to apply control strategies and often help reduce pesticide applications. This research is critical and timely for the grape and wine industry that deals with the threads of this devastating invasive insect pest.?
Animal Health Component
100%
Research Effort Categories
Basic
(N/A)
Applied
100%
Developmental
(N/A)
Goals / Objectives
The goal of this proposal is to estimate action thresholds for spotted lanternfly (SLF) management in two economically important V. vinifera cultivars, Cabernet Franc (red grape), and Chardonnay (white grape).Current knowledge indicates that repeated and heavy infestations of SLF reduce yield, wine quality and cause grapevine death. However, the insect density (SLF individuals per vine) able to cause yield losses and plant decline are unknown. Neither is known the number of yearly SLF infestations needed to kill a vine. This information is critical for SLF management because it helps determine the need to apply insect-suppressing techniques at any given time. The estimation of yield loss per insect, along with the estimated cost of insect control, will help determine economic decision levels for SLF.The estimation of economic thresholdsallows for a more rational pesticide use leading to environmental quality conservation and to economic benefits for growers.The specific research objectivesof this project are: 1) to determine the effect of various SLF densities on grapevine yield and wine quality, 2) to determine the number of SFL individuals that should trigger management actions, and 3) to determine the grapevine damage boundary caused by SLF.
Project Methods
Location. The field experiments of this proposal will be carried out at the Penn State Fruit Research and Extension Center (FREC) located in Adams County, PA. For our experiments, we will use 21-year-old vines of theV. viniferacultivar Cabernet Francand Chardonnay.Methods for objective 1Grapevines enclosed in cages of mesh fabric will be exposed to various numbers of SLF individuals early and late in the growing season, as described in the treatments below. The infestation levels will be 0, 1, 2...15 SLF individuals per shoot. Each vine will be an experimental unit and will be randomly assigned to only one level of SLF infestation.Treatments:a) Grapevines exposed to various infestation levels of SLFnymphsearly in the season. These vines will be caged and infested with SLF nymphs 1-4th from early Jun to mid-August only.b)Grapevines exposed to various infestation levels of SLFadultslate in the season. These vines will be caged and infested with SLF adults from mid-August to early November.c) Grapevines exposed to various infestation levels of SLFnymphs and adultsearly and late in the season.These vines will be caged and infested with nymphs (1-4th)in early June. In mid-August, the vines will be infested with adults. These vines will be enclosed in cages from June to November.Cage Effect.To determine the effect of the cage on yield loss and wine quality, vines without SLF will be enclosed in similar mesh cages used for the treatments a-c above. Each of the following controls will have five vines.Grapevines without SLF caged early in the season.These vines will be caged fromearly June- Mid August (control treatment a).Grapevines without SLF caged late in the season.These vines will be caged from mid-August to Novemberat (control treatment b).Grapevines without SLF, caged early and late in the season.These vines will be cagedfromearly June to November (control treatment c)Grapevines without SLF that will not be caged at any time during the growing season.These will be our absolute controls to calculate the effect of the cages on yield loss and wine quality.Effect of various levels of SLF infestation on yield loss.Yield will be quantified by counting the number of clusters and registering the total weight of harvested grapes per vine. The relationship between yield (number of clusters and total weight) and the number of SLF individuals will be calculated with a regression analysis. We will obtain aregression equation:Y = a + bx.Where Y = yield per vine, a = constant (intercept), b = slope (yield loss per number of insects), and x = number of insects per vine.The effect of the cages on yield will be calculated by an Analysis of variance (ANOVA) of the caged treatments and the uncaged controls followed by pairwise comparisons. If a significant effect of the cage is found for any of the treatments, the values of the corresponding treatment (a,borc) will be corrected for that difference before their use for regression analysis.Effect of various levels of SLF infestation on wine quality.Grapes will be picked from each of the treatments and either crushed and fermented within 12 hours or refrigerated with fermentation initiating within 48 hours.We will measure pH, degrees Brix and titratable acidity (TA) in flesh juice. The pH and Brix will be measuredon clarified juice, and the titratable acidity will be measured by titrating the juice with NaOH. Small scale replicated wine lots will be created from each of the treatments at a 50 ml scale using typical nutrient and yeast addition rates and using a minimum of 100 randomly selected berries per ferment. Wines will be fermented to dryness at 30°C with the cap reintegrated twice a day. The finished wines will be used to quantify total anthocyanins, total phenolics and tannins following the Adams Harbertson protocol (Harbertson et al. 2003). The characterization of wine aroma compounds from the small fermentations will be carried out using GC-MS coupled with SPME (solid phase microextraction). Authentic aroma standard for major red wine aroma compounds will be used for the creation of calibration curves, which will allow for quantification.Statistical analysis.The effect of varying SLF densities on grape juice pH, degrees Brix and TA, and on the total anthocyanins, total phenolics and tannins of the wines will be investigated with a regression analysis. The effect of the cage on these variables will be analyzed with ANOVA at alpha = 0.05; in the presence of significant differences, we will use post hoc tests to identify differences between treatment pairs.Methods for objective 2:The SLF economic decision levels will be calculated following the procedure described in Pedigo and Rice (2009) as follows:·Estimation of the yield loss per insect.This information will be obtained from objective one after quantifying the loss in yield from vines exposed to different SLF densities (insects per vine). From the regression equation obtained above, we will extract the yield loss per number of insects (b) to calculate the economic decision levels.·Determination of the gain threshold.The gain threshold is the amount of damage, yield loss or wine quality loss that justifies insect management; it will be calculated as follows:Gain threshold = (Management cost in dollars per acre)/(Market crop price in dollars per ton).The SLF management costs per season per acre will be estimated using spray records and other related information from vineyards that have been affected by SLF in the quarantine zone of Pennsylvania. A grape growers' survey will be developed to obtain the following information: number of years with SLF infestation, spray program to control SLF nymphs and adults (products, doses, frequency of applications, equipment used, cost of the products). Cost of labor (hours for insect scouting and product application) per area, number of tons per acre, and crop price per ton.·Determination of the loss that can be avoided by SLF management.We predict that opportune insecticide applications will prevent all loss that SLF may cause to vineyards; therefore, for this parameter, we will use a value of 1 (Pedigo and Rice, 2009).·Calculation of the Economic Injury Levels (EIL).Using the information described above, the EIL will be calculated as:EIL = [(Gain threshold (tons/acre)) / (loss per insect*Amount of loss avoided)].The Economic decision levels will be set lower than the EIL. For instance, 75% or 80% lower than the EIL to be conservative.Methods for objective 3:The damage boundary is defined as the lowest level of injury where damage can be measured (Pedigo and Rice, 2009). In this study, damage will be measured as yield loss and wine quality loss from vines exposed to various levels of SLF infestations as described in objective 1. The damage boundary is usually lower than the EIL, and damage below the boundary level does not require control (Pedigo and Rice, 2009).Efforts to improve knowledge of the target audience: The project PIs have extension appointments and meet regularly with grape growers in person and virtually to identify current needs and to share the results of our research projects. In addition to our meetings, the team will prepare an extension article with non-technical language targeted to grape growers and stakeholder.Evaluation of the project:OutcomeEvaluation1.We identify SLF densities that reduce grapevine yield and/or reduce wine quality.2.Based on experimental information of the effect of different insect densities on grapevine yield and wine quality, combined with data of SLF management costs, we estimate action thresholds for the management of this insect.3.We identify, experimentally the lowest number of SLF that decreases plant yield or reduces wine quality.4.The PIs will disseminate the results of this projects in various meetings and will develop short surveys to document the change in knowledge by the audience.