Insects show preferences for certain species or varieties of plants due to morphology, relative concentration of feeding stimulants, or other factors (Cavanagh and Hazzard 2006). When a more attractive plant is established around the field perimeter, insects moving in from wooded edges should concentrate in the perimeter trap crop and not feed on the main crop in the center. Control efforts can then be focused on trap crops, and potential costs can be minimized. Plants can also be used to attract natural enemies to a crop because they provide additional food resources in the form of nectar and pollen for predators and parasites. Their use can improve biological control and help reduce the need for pesticide sprays.
Michelle Infante-Casella, 2007
Demonstration Design: 'New England Blue Hubbard' (Cucurbita maxima) was planted as a perimeter trap crop around a field of 'Waltham' butternut squash in Mullica Hill, New Jersey, during the 2006 growing season.
Pest: Striped cucumber beetle (Acalymma vittatum, Fabricius)
Cucumber beetles vector bacterial wilt, which rapidly infects the plant at any growth stage. In infected plants, vascular tissues clog with bacteria, and the plant wilts, withers, and dies. Bacterial wilt is a major disease in New Jersey. Cucumber beetles overwinter in woods' edges around fields and enter fields from these edges.
Main Crop: Butternut squash
Trap Crop: 'New England Blue Hubbard' squash
Seeding: Squashes were seeded on 11 May with 72” between rows and 24” between plants in a row.
Set-up: Three rows of Blue Hubbard were seeded around the entire perimeter of the 8 acre field.
Observations: Beginning May 25 and continuing until the vines of the butternut began to run, we scouted twice a week, each time evaluating 100 random plants of each crop.
Control Measures: Measures were taken to control the pest when 10% of the plants observed had live beetles. The farmer made insecticide applications to the Blue Hubbard perimeter trap crop three times – on 31 May, 9 June, and 15 June.
Results:This demonstration trial showed that insecticide applications to control cucumber beetle can be reduced by using a perimeter trap crop. Additionally, sprays can be focused on the trap crop, reducing sprays on the cash crop.
This trial also established 'New England Blue Hubbard' squash as an effective perimeter trap crop for 'Waltham' butternut squash. Cucumber beetles were only found in the trap crop.
According to work out of Cornell, butternut squash was less attractive to cucumber beetles and also less susceptible to bacterial wilt. Their results corroborate our findings – attractive trap crops, such as Blue Hubbard can be used to control cucumber beetles, particularly on less attractive main crops, i.e. butternut squash. See: Attractiveness to Cucumber Beetles.
Does this study apply to my farm?
This study observed perimeter trap cropping on a relatively large plot of butternut squash – 8 acres. According to the USDA organic survey, squash is grown organically on 26 acres across 28 farms in New Jersey. On smaller plots, the trap crap may be too close to the main crop, enabling pest movement and damage to the main crop. In this study three rows of perimeter trap crop were seeded with rows 6' apart.
For best results, the trap crop should be located near edges so as to intercept pests as they move from wooded edges into the field. Also, in this study, squash were seeded in May. Typically, winter squash are seeded in June and July. Pest pressure will be higher later in the season.
What about the beetles in the trap crop?
Adults lay eggs on the trap crop. The larvae feed below ground, emerging in mid-summer. Destroy the trap crop after the overwintering generation begins to disappear and before adults emerge. The trap crop must be mowed and disked. This should also help reduce populations over the long-term.
How else can the pest be controlled in the trap crop?
According to Cornell research, the materials available for organic production fail to provide adequate control of the striped cucumber beetle. Materials tested include Entrust, Cidetrak D, Pyganic 5.0, Neemix 4.5, and Surround. In their study, no treatment reduced percent defoliation compared to the untreated control. Though not significantly different from the control, Entrust WP reduced damage to the greatest extent.
Work from University of Massachusetts has shown kaolin to be most effective when compared to pyrethrin and spinosad. Kaolin is a protectant and must be applied beforebeetles move to the main crop. See: Managing Striped Cucumber Beetle in Vine Crops from University of Massachusetts.
Additionally, farmers have observed control with pyrethrum. Pyrethrum may be considered as a tool to manage beetles on the trap crop before they move into the main crop. See: Resource Guide for Organic Insect and Disease Management.
How can I protect my main crop?
Always consider planting tolerant varieties. Butternut squash, for instance, is less susceptible to bacterial wilt and less attractive to cucumber beetles. See: Attractiveness to Cucumber Beetles.
For high-value crops, floating row covers can be used to exclude cucumber beetles. This technique may be cost-prohibitive. If using row covers, remove covers at flowering so as not to reduce pollination.
Kaolin has protective activity and, if applied before beetles move to the main crop, may be effective. See: Managing Striped Cucumber Beetle in Vine Crops from University of Massachusetts.
As always, follow basic cultural practices for insect control, including crop rotation. Additionally, plow deeply and cultivate after harvest to reduce overwintering populations.
How do I know if my squash has bacterial wilt?
Cut the wilted stem close to the crown and rejoin the cut surfaces. Slowly pull them apart. If there is bacterial slime, which appear as thread-like strand extending from one cut end to the other, the plant is infected.
What are some other good sources of information?
Check the Organic Production Guide from New York State IPM and Cornell University for information on pesticides labeled for use in organic cucurbit production and always be sure to double check with OMRI and your certifier before using.
Also see: Options for Managing Bacterial Wilt Affecting Cucurbit Crops from Cornell University and Cucumber Beetles: Organic and Biorational Integrated Pest Management from ATTRA.
Michelle Infante-Casella and G. Ghidiu, 2008
Demonstration Design: 'New England Blue Hubbard' (Cucurbita maxima) and 'Bird House Gourd' (Langenaria siceraria)were planted as perimeter trap crops around fields of pumpkin at the Rutgers Agricultural Research and Extension Center in Bridgeton, New Jersey in June to July of 2008.
Pests: Striped cucumber beetles (Acalymma vittatum (Fabricius), spotted cucumber beetles (Diabrotica undecimpunctata howardi Barber) and squash bug (Anasa tristis)
Main Crop: Pumpkin 'New England Pie'
Trap Crops: 'New England Blue Hubbard' (Cucurbita maxima) and 'Bird House Gourd' (also known as 'Bottle Gourd') (Langenaria siceraria)
Seeding and Set-Up: All were seeded on June 11, 2008. In two fields, pumpkin was seeded in ten rows, 150' long and 6' apart, with 3' between plants. Two rows of a trap crop ('New England Blue Hubbard' in one field and 'Bird House Gourd' in the other) were seeded at the same spacing around each pumpkin field. In a third field, 'New England Pie' pumpkin was seeded in 14 rows 150' long and at the same spacing. Buffers of 100' separated the three demonstration fields.
Observations: Pumpkin leaves and stems were scouted daily July 11 – July 18.
Beetles: On the last scouting date, beetle numbers were highest in the 'New England Blue Hubbard.' Low numbers of live beetles were found on 'Bird House Gourd.' More cucumber beetles were found on pumpkin plants in the field without a perimeter trap crop compared to pumpkin plants in fields with perimeter trap crops. (Fewer beetles were found on pumpkins in fields with trap crops.)
Squash bugs: During all scouting dates, squash bug numbers were highest in the 'New England Blue Hubbard.' Low numbers of squash bugs were found on 'Bird House Gourd.' For all but the last scouting date, more squash bugs were found on pumpkin plants in the field with the 'New England Blue Hubbard' squash perimeter trap crop compared to pumpkin plants in the field without a perimeter trap crop and those in the field with the 'Bird House Gourd' trap crop.
Take-Home: Perimeter trap cropping may be a useful method for managing cucumber beetle populations in pumpkin. 'New England Blue Hubbard' may be a suitable perimeter trap crop for cucumber beetle control in pumpkin.
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