Progress report for GNE24-306
Project Information
Maggots (Delia spp.) are devastating below-ground pests of onions and cabbage in the Northeast. These crops are among the most valuable vegetable crops in this region, and damage can cause yield losses of up to 50%. Over one-third of the onion acreage and nearly all of the cabbage acreage are transplanted, and growers typically relied on at-planting applications of chlorpyrifos to control maggots. The EPA banned chlorpyrifos in 2022, and now there is a demand to identify effective insecticides that will protect transplanted onion and cabbage fields from maggots. Research is needed to identify reduced-risk insecticides that are effective against maggots as well as safe for pesticide applicators and the environment. Additionally, further research is needed to examine the impact of entomopathogenic fungi (EPF) and entomopathogenic nematodes (EPN) as insecticides for controlling maggots in transplanted crops. Anticipated benefits from this project include improving crop production by decreasing pest damage with safer pest management solutions for applicators and the environment and mitigating resistance development by identifying a series of insecticides that could be used in rotation strategies.
The goal of this project is to identify reduced-risk insecticides to protect onion and cabbage transplants from maggot pests that are also safe for pesticide applicators and sustainable for these cropping systems. To achieve this goal, I propose the following objectives:
- Identify reduced-risk insecticides applied as tray drenches to control onion maggots (D. antiqua) in onions. We hypothesize that all insecticides will provide an acceptable level of onion maggot protection.
- Identify reduced-risk insecticides applied as tray drenches to control cabbage maggot (D. radicum) in cabbage. We hypothesize that all insecticides will provide an acceptable level of cabbage maggot protection.
The purpose of this project is to evaluate the performance of reduced-risk insecticides for the control of maggot pests in onions and cabbage. Insecticides considered “reduced-risk” have a low impact on human health, lower toxicity to non-target organisms, and a low potential for groundwater contamination. The onion maggot (Delia antiqua) and cabbage maggot (Delia radicum) are among the most important early-season pests of transplanted onions and cabbage in the Northeast, respectively. Seedcorn maggot (Delia platura) also attacks both crops and has always been considered a secondary pest relative to D. antiqua and D. radicum (Salgado & Nault unpublished data, Savage et al., 2016). To protect these crops from all maggot species, chloryprifos was used at planting in transplanted onion and cabbage fields. However, the EPA banned chlorpyrifos from all food crops, including onions and cabbage, leaving growers with no known effective alternatives. Research is needed to identify insecticides that are effective for protecting onion and cabbage from maggots, especially products that are considered reduced-risk that are safer to the applicator and environment.
Onions and cabbage are two of the most important vegetable crops in the Northeast. Onion production in New York constitutes 97% of the production in the northeastern United States and ranks eighth in the country. Cabbage production in New York ranks in the top three nationally, with 5,000+ acres harvested per year (USDA NASS, 2023). Sales of both crops exceed USD 100 million annually (USDA NASS, 2023).
In the northeastern US, onions are primarily grown in soils drained from swamps called “mucks,” which are soils with high organic matter and nutrient content (Stephens, 1955). Onions are transplanted between April and early June in the Northeast. The two most common types of onion transplants are either bare root (imported from Arizona) or plugs (grown locally or imported from Canada). Cabbage is grown on mineral soils and is transplanted between late April and July. The two most common types of cabbage transplants are also either bare root (imported from Georgia and Florida) or plugs (grown locally). Because onions and cabbage are transplanted in the spring when soil conditions are typically cool and wet, maggots (Delia spp. [Diptera: Anthomyiidae]) are a serious pest problem for these growers. In the onion crop, onion maggot (D. antiqua) and seedcorn maggot (D. platura) occur throughout northern onion production regions in the US, but differ in abundance and pest status in each region. Preliminary results (Salgado & Nault unpublished data) showed that the onion maggot is more abundant than the seedcorn maggot in New York onion fields. In cabbage, the cabbage maggot (D. radicum) was reported to be the most abundant Delia species (Savage et al., 2016). For all maggot species, flies lay their eggs on or at the base of onion or cabbage plants, and larvae move into the root zone and begin feeding. Damage occurs mainly on the below-ground portion of plants, reducing yields by decreasing stand counts in heavy infestations (Nault et al., 2006; Salgado et al., 2023).
Onion growers have no effective insecticide options for protecting onion transplants from maggots. Cabbage growers can use directed foliar applications of pyrethroid insecticides (e.g., Mustang Maxx and Hero) when flies are active, but this approach has generated inconsistent results. Recently, preliminary field trials have shown that at-plant applications of cyantraniliprole (Verimark) and chlorantraniliprole (Coragen) can protect transplanted cabbage from D. radicum (Salgado et al., 2023). However, very little is known about the efficacy of reduced-risk insecticides and biological products for protecting onion and cabbage transplants from maggots.
Research is needed to identify insecticides that are effective against these maggot pests but are safe for pesticide applicators and sustainable for these cropping systems. This project will contribute to Northeast SARE’s outcome statement by finding actionable solutions by doing on-farm research that can help growers mitigate pest damage and maintain crop yields, gain more knowledge to reduce reliance on insecticides that are harmful to applicators and the environment, and indirectly support these agricultural businesses’ sustainability and profitability.
Research
Objective 1: Identify reduced-risk insecticides applied as tray drenches to control onion maggot (D. antiqua) in onions.
Treatments. The experiment will include the following treatments: 1) No insecticide, 2) commercial formulation of spinosad, 3) commercial formulation of cyantraniliprole, 4) commercial formulation of Beauveria bassiana, 5) commercial formulation of Metarhizium sp., and 6) commercial formulation of Steinernema feltiae and Heterorhabditis bacteriophora (Table 1.). See the attached protocol for calculations.
Table 1. List of treatments with rates for reduced-risk insecticides for onion.
|
Trt# |
Products |
Active ingredient(s) |
Rate of formulated product(s) |
Rate per plant |
Rate per tray |
|
1 |
Untreated control |
- |
- |
- |
- |
|
2 |
Entrust SC |
spinosad |
8 fl oz/acre |
0.0013 ml |
0.75 ml |
|
3 |
Verimark |
cyantraniliprole |
13.5 fl oz/acre |
0.0022 ml |
1.24 ml |
|
4 |
BoteGHA ES |
Beauveria bassiana Strain GHA, 11.3% |
64 fl oz/acre |
0.0103 ml |
5.93 ml |
|
5 |
LALGUARD M52 OD |
Metarhizium brunneum strain F52 |
80 fl oz/acre |
0.0128 ml |
7.37 ml |
|
6 |
NemAttack™ & NemaSeek™ Combo Pack Sf/Hb |
Steinernema feltiae & Heterorhabditis bacteriophora |
250,000,000 infective juveniles per acre |
1,356 infective juveniles |
781,056 infective juveniles |
Site selection and experimental design. Field trials will be conducted on 1 commercial farm in Oswego, NY, and 1 commercial farm in Wayne County, NY, which were selected because growers have reported high infestations of maggots. Trials will be transplanted in April/May 2025 and 2026 and maintained by Salgado and temporary staff. Plots will contain two rows of onions, each 15 ft long. Treatments will be arranged in a randomized complete block design, and each treatment will be replicated 5 times. Plant density will be 3 plants per foot hand planted, 45 plugs per row, and 90 plugs per plot (2 rows); 5 reps x 90 plugs =450 plugs per treatment. 300 plugs x 6 treatments = 2,700 plugs per experiment.
Treatment applications:
Procedure for Applying Entrust to ONE TRAY:
- Apply 1 liter of water to trays to wet plants and soil surface in plugs
- Spray 0.75 ml of Entrust per tray as equally as possible (volume can vary) 24 hours before transplanting.
- Apply 1 liter of water to rinse Entrust residue from leaves and soil surface down towards the roots.
Procedure for Applying Verimark to ONE TRAY:
- Apply 1 liter of water to trays to wet plants and soil surface in plugs
- Spray 1.24 ml of Verimark per tray as equally as possible (volume can vary) 24 hours before transplanting.
- Apply 1 liter of water of water to rinse Verimark residue from leaves and soil surface down towards the roots.
Procedure for Applying BoteGHA ES to ONE TRAY:
- Apply 1 liter of water of water to trays to wet plants and soil surface in plugs
- Spray 5.93 ml of BoteGHA ES per tray as equally as possible (volume can vary)
- Apply 1 liter of water of water to rinse BoteGHA ES residue from leaves and soil surface down towards the roots.
Procedure for Applying Lalguard M52 OD to ONE TRAY:
- Apply 1 liter of water to trays to wet plants and soil surface in plugs
- Spray 7.37 ml of Lalguard M52 OD per tray as equally as possible (volume can vary) 24 hours before transplanting
- Apply 1 liter of water of water to rinse Lalguard M52 OD residue from leaves and soil surface down towards the roots.
Procedure for Applying NemAttack™ & NemaSeek™ Combo Pack Sf/Hb to ONE TRAY:
- The amount of NemAttack™ & NemaSeek™ Combo Pack needed per 288 cell tray (which contains 576 plants) is 781,056 IJs of Steinernema feltiae and Heterorhabditis bacteriophora, respectively, which has to be applied 24 hours before transplanting.
- Once we get the product, we need to measure the number of infective juveniles in 1 ml of water with 1 gram of NemAttack™ & NemaSeek™ Combo Pack to calculate the number of grams we need to put per tray to get 781,056 infective juveniles per tray.
Data collection and analysis.
Treatment verification. To verify that the EPFs and EPNs were viable before application and contained in the soil from the farms, one plastic cup (120 ml volume) will be filled with autoclaved soil (100 g/cup), one with soil from a representative sample from the farms before transplanting (100 g/cup), and one soil sample (100 g/cup) will be extracted from the EPFs and EPNs-treated plots to isolate organisms from the soil samples to evaluate establishment of the treatments at the last day of the evaluation period. In these plastic cups, 10 larvae of Galleria mellonella (fourth instar) will be used to measure the infectivity of the EPFs and EPNs from the commercial products and to evaluate if there are any other EPFs and EPNs from soil samples from the farms. Cups will be incubated at 25 °C and examined daily for collection of dead larvae, which will be carefully washed with distilled water and placed for 30 seconds in a sterile 1% sodium hypochlorite solution. Fungi or nematodes obtained from the surface of larvae will be identified to evaluate recovery of EPFs and EPNs treatments applied.
Treatment evaluation. The number of plants wilting and dying from maggot feeding will be recorded at least one time per week from late-May until early July (6 weeks). A final plant stand count will be taken for all plots from early to mid-July. The percentage of plants killed by maggots will be determined by dividing the number of plants killed by maggots by the sum of plants killed by maggots plus the number of plants remaining during the final stand count and then multiplying by 100. Data will be analyzed using generalized linear mixed models (PROC GLIMMIX, SAS® Institute 2013) in which treatment will be considered a fixed factor and replication a random factor in the model. Treatment means (Least Squares means) will be compared using Tukey’s HSD Test at P < 0.05.
Performance Measure. We expect to identify insecticide(s) applied as a tray drench treatment that will effectively protect the onion crop from maggot damage. Treatments with ≤5% maggot damage will be considered commercially acceptable.
Objective 2: Identify reduced-risk insecticides applied as tray drenches to control cabbage maggot (D. radicum) in cabbage.
Treatments. The experiment will include the same treatments as objective 1 but with different rates adjusting to the plant density (Table 2). See the attached protocol for calculations.
Table 2. List of treatments with rates for reduced-risk insecticides for cabbage.
|
Trt# |
Products |
Active ingredient(s) |
Rate of formulated product(s) |
Rate per plant |
Rate per tray |
|
1 |
Untreated control |
- |
- |
- |
- |
|
2 |
Entrust SC |
spinosad |
10 fl oz/acre |
0.0170 ml |
4.90 ml |
|
3 |
Verimark |
cyantraniliprole |
13.5 fl oz/acre |
0.0229 ml |
6.60 ml |
|
4 |
BoteGHA ES |
Beauveria bassiana Strain GHA, 11.3% |
64 fl oz/acre |
0.1086 ml |
31.28 ml |
|
5 |
LALGUARD M52 OD |
Metarhizium brunneum strain F52 |
80 fl oz/acre |
0.13578 ml |
39.11 ml |
|
6 |
NemAttack™ & NemaSeek™ Combo Pack Sf/Hb |
Steinernema feltiae & Heterorhabditis bacteriophora |
250,000,000 infective juveniles per acre |
14,349 infective juveniles |
4,132,512 infective juveniles |
Site selection and experimental design. Field trials will be conducted on 1 commercial farm in Genesee County, NY, and 1 farm in Ontario Country, NY, selected because growers have reported high infestations of maggots. Trials will be transplanted in April/May 2025 and 2026 and maintained by Salgado and temporary staff. Plots will contain two rows of cabbage, each 20 ft long. Row spacing will be 32 inches, and plots will be separated from each other within rows by 5-foot. Plant spacing will be 10-inches per plant (1.2 plants per foot) for a planting density of 17,424 plants/acre. Treatments will be arranged in a randomized complete block design, and each treatment will be replicated 5 times.
Treatment applications:
It will be performed as outlined in objective 1 using the rates in Table 2.
Data collection and analysis.
Treatment verification. It will be performed as in objective 1.
Treatment evaluation. Twenty plants per plot (including all stunted plants) will be sampled 40 days after transplant to record the cabbage maggot infestation per treatment. Plants will be uprooted with a trowel and inspected for the presence of cabbage maggot larvae and pupae. Plant roots will be rinsed in water to remove excess soil and checked for cabbage maggot feeding damage, which will be characterized by galleries in the roots and lower stem. The presence of maggots and their damage will qualify as an infested plant. The percentage of infested plants by maggots will be determined by dividing the number of plants with the presence of maggots and pupae by the sum of plants sampled by plot and then multiplying by 100. Data will be analyzed using generalized linear mixed models (PROC GLIMMIX, SAS® Institute 2013) in which treatment will be considered a fixed factor and replication a random factor in the model. Treatment means (Least Squares means) will be compared using Tukey’s HSD Test at P < 0.05.
Performance Measure. We expect to identify insecticide(s) applied as a tray drench treatment that will effectively protect the cabbage crop from maggot damage. Treatments with ≤5% maggot damage will be considered commercially acceptable.
Reporting Period: August 2024 to January 2025
During this reporting period, we engaged with a representative from Certis Biologicals to discuss their range of biological products. Following these discussions, Certis agreed to provide us with select products for our trials. Instead of using BotaniGard Maxx, we opted to test BoteGHA ES to focus on the specific effects of Beauveria bassiana. Unlike BotaniGard Maxx, which combines Beauveria bassiana with a pyrethroid, BoteGHA ES contains only Beauveria bassiana.
Additionally, we conducted preliminary meetings with our collaborators to finalize the treatment list for the upcoming field season and to strategize preparation efforts for our trials. In February and March, we plan to begin contacting grower collaborators to discuss space allocations and plant requirements for the field trials.
Education & Outreach Activities and Participation Summary
Participation Summary:
The results and outputs from this project will benefit the target stakeholder group (onion and cabbage growers) by helping them select reduced-risk insecticides to control maggots in onions and cabbage. To reach our immediate stakeholders, I will publish our results in trade journals, such as Onion World, as well as update online associated content with onion maggot and cabbage maggot for Cornell Cooperative Extension. I will also present maggot management information at the Empire State Expo organized by the New York State Vegetable Growers Association, which is presided over by our collaborator Brian Reeves, and at regional onion meetings like the Oswego Onion Growers Meeting and the Onion School in Orange County in collaboration with our collaborators from Cornell Cooperative Extension, Christy Hoepting, and Ethan Grundberg. They will also receive presentation materials and fact sheets. The number of visits and downloads will measure the impact of fact sheets and newsletters on the stakeholder group. To reach a wider audience of onion growers in the northeast, the New England Vegetable Growers Conference, the Mid-Atlantic Fruit and Vegetable Convention, and the Great Lakes Fruit, Vegetable, and Farm Market Expo will also be considered. To ensure that our findings are also disseminated into scientific communities, research outcomes will be published in peer-reviewed journals and presented at professional meetings such as the Entomological Society of America.