Using Banker Plant Systems for the Management of Aphids on Greenhouse Crops

Commodities

• Vegetables: cucurbits, tomatoes

Practices

• Pest Management: biological control, cultivation, integrated pest management, prevention

During the early 2023 growing season, we established banker plants in our greenhouses for the management of aphids on our cucumber crop. We considered this pilot experiment successful, which led us to believe banker plants may be an effective tool for aphid management on greenhouse crops in the Southeast. The goal of this proposal is to replicate our previous banker plant trials to generate data which can be shared with other growers in the Southeastern region to demonstrate the efficacy of banker plants for aphid management, expand our trials to include a second banker plant system intended to control aphid pests of tomatoes, and provide data on the cost of implementing the banker plant method for these crops. We believe this will benefit growers by providing knowledge of a potentially cost-effective greenhouse aphid management technique that reduces the need for chemical pesticide inputs.

This project will utilize two banker plant systems. The first of these uses a barley banker plant infested with the bird cherry
oat aphid (Rhopalosiphum padi), which is an alternative host for the wasp Aphidius colemani, a parasitoid of melon aphid (Aphis gossypii). The second uses a fava bean banker plant infested with pea aphids (Acyrthosiphon pisum) as a host for the wasp Aphidius ervi, which parasitizes larger aphids such as the potato aphid (Macrosiphum euphorbiae). We have previously identified melon and potato aphids as common aphid species on our greenhouse cucumbers and tomatoes, respectively.

Experiments will take place in a greenhouse divided into two 4000 square foot growing spaces. During the Spring growing season lasting between January and June, one of these spaces will be used to grow tomatoes, and the other will be used to grow cucumbers. During the Fall growing season, between August and December, one space is taken out of production to go into cover crops, so experiments will take place in a single growing space containing tomatoes and cucumbers.

Banker plant materials and beneficial insects will be purchased primarily from a commercial insectary (IPM Laboratories, Inc., Locke, NY). All practices for purchasing, planting, and maintaining banker plants follow manufacturer recommendations. Fava bean seed will be purchased 3 weeks prior to planting tomatoes, and pea aphids will be ordered as soon as fava bean plants have produced 5 pairs of leaflets. 250 A. ervi wasps will be released 1 week after introducing pea aphids to the banker plants to allow the aphids time to reproduce. Barley banker plant starter kits will be ordered 2 weeks prior to planting cucumbers. After 2 weeks, we will release 500 A. colemani wasps. For both fava bean and barley banker plants, we will place 2 of each banker plant adjacent to their respective crops (fava bean near tomatoes, barley near cucumbers). Banker plants will be maintained as instructed by the manufacturer, and new banker plants will be started every other week or as needed. Any additional purchases or parasitoids after the initial release will be noted.

To determine the efficacy of A. ervi and A. colemani banker plants for aphid management, we will select 12 tomato plants and 12 cucumber plants for observation. Because of the proximity of some plants to fans at the front of the greenhouse, which may interfere with aphid or parasitoid establishment, we will divide our plants into 2 blocks based on proximity to the fan, with 6 plants per block. These plants will be deliberately infested with aphids (M. euphorbiae for tomato, A. gossypii for cucumber), and half of them will be caged to exclude parasitoid wasps or other natural enemies. Cages will consist of a 200 square foot fine mesh garden cloth laid over a 2 by 3 foot frame made of PVC pipe, which will rest above the plants on trellising wires. The farm assistant will scout these plants once per week and count and average all aphids and aphid mummies on three leaves from each plant, as well as count all aphid mummies on the banker plants. Additionally, the farm manager and farm assistant will scout the entire crop area once per week to record a subjective measurement of the level of aphid infestation on both crops: 0 = no infestation, 1 = minor infestation, 2 = moderate infestation, 3 = severe infestation.

For the duration of the experiment, we will keep detailed notes on banker plant growth and maintenance, as well as of all costs associated with the project. Estimated costs for any materials purchased prior to the start of the experiment, as well as the number of hours spent on banker plant maintenance and scouting, will also be recorded. This will allow us to estimate the overall costs associated with establishing and maintaining banker plants for this period of the growing season.