Progress report for GNE22-288
Project Information
Lycorma delicatula, spotted lanternfly (SLF), is an invasive plant hopper from Asia and a major pest to the agricultural and forestry industries in the Mid-Atlantic region that was first detected in New Jersey in 2018. It is present at over 75% of vineyards in the state, with most. SLF is a highly polyphagous species that feeds on the plant phloem of over 100 plant taxa. A key host is cultivated grape which SLF adults congregate on in late summer/early fall. Feeding on grapevines has been associated with decreased grape growth rates, overwintering ability, and reduced crop yield. An economic threshold of 10 SLF adults/vine used in South Korea has been exceeded in many New Jersey vineyards, with some experiencing pressure of 200 SLF/vine. Waves of SLF adults colonize vines for 4-8 weeks, requiring multiple insecticide applications. On average growers apply 2 to 6 insecticide sprays just for managing SLF adults during this short time. This project aims to assess the efficacy of insecticides currently used in vineyards against SLF and the in-field residual activity of each for resistance management. This builds off previous research that has identified the peak dispersal time and residence time in New Jersey grapes as well as caged insecticide trials. Results will guide grower decisions on timing insecticide applications and materials that match preharvest restrictions. Efficacy results of this study will be disseminated directly to farmers through grower conferences and Rutgers extension blog posts.
- Evaluate the residual efficacy of foliar-applied insecticides in vineyards against SLF adults.
Three pyrethroids and one noenicitinoid will be tested that varying reported residual activity. One application will be made at the peak of SLF movement into vineyards. Using decease individuals and live counts on vines percent mortality will be tracked over the course of 26 days for each of the tested insecticides to identify its efficacy over time. This will help guide grower decisions for materials used within their vineyards.
- Assess SLF female physiological state during movement.
Dead individuals collected will be sexed and ranked based on the percent fat shown on the exterior of their abdomen to assess fat body accumulation over time. Females will be dissected to identify mated status over 26 days. This will allow us to equate fat body accumulation with timing of SLF movement into vineyards. There are currently no quantifiable metrics to predict exact time of movement.
- Quantify SLF feeding impact on primary bud growth.
Primary bud formation metrics will be recorded on vines exposed to SLF feeding from fall 2022 at vineyard edge and vineyard center. This will help equate vine damage with feeding density providing insight into potential SLF feeding thresholds.
The purpose of this project is to evaluate the residual efficacy of foliar-applied insecticides on grapevines against adult SLF to reduce the number of insecticide applications to reduce environmental impact and increase worker safety. Our results will guide grower decisions on compounds used for insecticide application that incorporate preharvest intervals. Peak adult SLF dispersal into vineyards occurs in early September and continues for several weeks. This movement coincides with preharvest and harvest periods where there is increased human activity within the vineyard. The compounded effects of gregarious feeding over the span of several years can result in significant economic losses for growers. SLF density increases feeding pressure on grapevines acting as a plant stressor and is associated with decreased grape growth rates, overwintering ability (Song 2010), and reduction of crop yield (Urban 2020, Leach and Leach 2020).
Since its first detection in 2018, approximately 75% of New Jersey vineyards have some level of SLF pressure resulting in many growers apply 2 to 6 additional insecticide applications targeting SLF. Based on our surveys, vineyards in New Jersey with high SLF population densities can have upwards of 200+ SLF/vine for multiple weeks despite insecticide applications.
Penn State evaluated the efficacy and residual activity of several of the proposed insecticides on growing grape terminals with variable results. Their trials involved sleeve cages with 10 adults exposed to the material for 24 hours before removal. This process was repeated for eight times points between 1 to 26 days (Leach 2021). Their results have helped shape management recommendations, however, SLF behavior is altered when enclosed in a cage and SLF at this critical time stage are feeding on canes and trunks. A more a curate evaluation on residual activity may be needed to effectively manage the new waves of adults dispersing into the vineyard. The insecticides identified with the longest residual by Penn State plus the insecticide most commonly used pre-harvest will be evaluated in consideration with their pre- -harvest interval. SLF adult pressure coincides with harvest for grapes and all three of these factors need to be considered when choosing which insecticide to apply. The residual effects of these compounds will guide grower application as part of their management program.
Research
- Evaluate the residual efficacy of foliar-applied insecticides in vineyards against SLF adults.
To evaluate the residual efficacy of foliar-applied insecticides in vineyards against SLF adults four insecticides will be assessed. The treatments to be evaluated are an untreated control, a neonicotinoid, thiamethoxam (Actara) and three pyrethroids, cypermethrin (Mustang Max), fenpropathrin (Danitol), and bifenthrin (Brigade). These insecticides were selected based on their previously reported residual activity. Neonicotinoids demonstrated > 60% mortality up to 5 d after application while pyrethroids had a much longer residual efficacy lasting up to 15-21 d after application (Leach 2021). There will be five treatments, each replicated four times. Treatments will be applied to 5-yr old grapes using a hand-held CO2 pressurized sprayer. Each of the four insecticides will be applied once at the start of peak SLF movement. An additional treatment will be included for a potential grower spray program using the residual results found by Leach (2021) such as 1) Danitol 2) Actara 3) Mustang Maxx 4) Brigade post-harvest (Table 1) that integrates PHI with expected residual activity. The first two rows of the vineyard block closest to a wooded edge will be used since SLF has a distinct border effect with 54% of the populations congregating within the first 15m of the vineyard border (Leach and Leach 2020). Insecticide treatments will be applied to five vines with an additional five vines left untreated between treatments. SLF exposure to insecticide will be based on the natural influx of SLF adults moving into the vineyard. Nielsen (unpublished) has reported SLF adult persistence within the vineyard for 3 weeks using mark-release-recapture methods. Percent mortality will be assessed at eight time points, day 1, 3, 5, 7, 11, 15, 21 and 26 for the first 4 treatments (Leach 2021). Precent mortality will be assessed for the 5th treatment at the same eight intervals but will be continued until there are no more SLF present within the vineyard. Dead individuals will be removed and frozen for the treatment areas at each check day and used for Objective 2. A one-way ANOVA will be used for analysis comparing the four treatments.
|
Trade Name |
Active Ingredient |
Class |
Rate per acre (oz.) |
PHI (days) |
REI (hrs) |
Residual Activity (days) |
Max. use per season (oz) |
|
Actara 25WDG |
thiamethoxam |
Neonicotinoid |
3.5 |
5 |
12 |
<21 |
7 |
|
Mustang Maxx 0.8EC |
cypermethrin |
Pyrethroid |
4 |
1 |
12 |
<7 |
24 |
|
Danitol 2.4EC |
fenpropathrin |
Pyrethroid |
21.33 |
21 |
24 |
>26 |
42.66 |
|
Brigade 10WSB |
bifenthrin |
Pyrethroid |
8-16 |
30 |
12 |
21 |
16 |
- Assess timing of SLF movement into vineyards with fat body accumulation.
To assess fat body accumulation and mated status, dead individuals will be sexed, measured, and dissected from each of the treatments and check points. Only females will have their yellow abdominal area measured (Urban unpublished) and dissected for mated status. Wolfin et al. (2019) showed a relationship between increased yellow abdomen area with limited flight capability and mated status. Presence of the male spermatophore and oocyte development will also be recorded. A one-way ANOVA will be used for analysis.
- Quantify SLF feeding impact on primary bud growth.
To determine SLF feeding impact on primary bud development density of individuals will be compared from the first grape row to that of the 10th row. A series of bud formation metrics will be used to measure primary, secondary, and tertiary bud formation in the spring 2023. A one-way ANOVA will be used for analysis.
Objective 1: In Progress
Evaluate the residual efficacy of foliar-applied insecticides in vineyards against SLF adults. SAREupdate1.15.23graphs
The insecticide trial was conducted in the Summer of 2022 at RAREC on two grape varieties (chardonnay and chambourcin). Chemicals assessed included Actara, Mustang Maxx, Danitol, and Brigade. Treatments were checked three times per week for live SLF on vines and dead insects collected and stored in the freezer for future dissection. The trial lasted for a total of 27 days. Materials with shorter residual activity were reapplied as needed in accordance with the label instructions. This resulted in three sprays for Mustang Maxx, two sprays for Danitol, and one spray for Actara and Brigade for the duration of the experiment.
All insecticides had a high initial knockdown effect, with Bridage and Danitol performing the best. All insecticides showed large oscillations in their residual efficacy. We suspect this volatility may be a result of extremes in temperature despite time of sampl ing being consistent throughout the trial. Days with higher temperatures had greater SLF movement and resulting in lower average percent mortality. Extended periods of cold, rain, wind, or hurricane conditions hindered SLF movement and percent mortality resulting in higher average percent mortality.
General observations showed an overall higher number of SLF in the Actara (neonicotinoid) treatments then with other insecticides (pyrethroids). Insecticides were ranked for best residual efficacy as follows: 1) Brigade, 2) Actara, 3) Danitol, and 4) Mustang Maxx. However, there were no statistically significant differences between the insecticide’s residual efficacies. Based on previous studies, Danitol was expected to have higher residual efficacy longer than 13 days. Actara outperformed expectations and previously predicted residual efficacy duration.
An additional year of data for 2023 needed to be collected due to environmental extremes during the course of the trial in 2022. Differences in residual efficacy were observed between insecticides by sampling year. Data analysis for this data is still in progress.
Objective 2: In progress
Assess timing of SLF movement into vineyards with fat body accumulation.
- SLF females collected and stored for dissection
Objective 3: In progress
Quantify SLF feeding impact on primary bud growth.
To asses damage caused by adult feeding of overwintering vines SLF counts were done weekly for the same 30 vines at RAREC for the duration of adult feeding in fall of 2022. This was done for two grape varieties; Chardonnay (15 vines) and Chambourcin (15 vines). Three shoots were collected at random from each sampled vine in March of 2023. Shoots were stored in buckets with water for 48 hours, to increase accuracy of identification of bud death. 50 buds were dissected for each shoot and assessed for bud primary, secondary and tertiary mortality. Percent mortality for buds was identified for each vine. Analysis is still in progress. Bud mortality will be analyzed via regression against the average number of SLF feeding on the vines.
Education & Outreach Activities and Participation Summary
Participation Summary:
Results obtained from these studies will be published in Arthropod Management Tests and presented at professional conferences such as Cumberland Shenandoah fruit workers conference 2022 and the Entomological Society of America Eastern Branch meeting in 2023. To make this information easily accessible to growers, these results will be presented at grower meetings including New Jersey grape camp New Jersey Fruit and Vegetable EXPO, and in-season twilight meetings. Online publications will be posted on the Rutgers NJAES blog website “Plant Pest Advisory”. Data obtained from this study will be applicable across different states as the spread of SLF unfolds. Grower recommendation website postings will be written to reach a wider audience.