Four lined plant bugs are emerging now in southern areas and will be emerging over the next week or two further north. Look for curling and spotting on the tops of the new shoots and small bright red nymphs that hide behind leaves as you approach the plant. Now is the best time to try to manage the insects before they cause significant damage. If you had a problem with them last year, they would likely cause similar or more problems this year. If you did not have them last year, don’t assume you will not have a problem. Populations tend to build over time. It is best to make at least two applications a week apart starting with the very first signs of feeding damage. It is very important to get good spray coverage and follow the directions on the label for optimal timing during the day. If possible, use a pressurized sprayer with a pressure gauge to ensure a consistent fine mist that penetrates deeply into the plant and can swirl through the plant canopy. For more information on sprayers, visit Sprayers 101 at https://sprayers101.com/.
Lavender growers now have a few pest control product options that may help in managing four lined plant bug when lavender is grown as a culinary herb. Pyganic Crop Protection EC 1.4 II (pyrethrins) was recently registered for control of aphids, cutworms, cabbage loopers, and leafhoppers in Crop Group 19 which includes lavender. Insecticidal soaps like Safer’s Trounce (soap + small amount of pyrethrins), Opal and Kopa (just soap) were already registered for control of aphids in lavender. When applying these products for control of labeled pests, they will likely also suppress four lined plant bug. Pyganic will likely be more effective for all ages of nymphs, whereas the insecticidal soaps are likely most effective at the very young nymphal stage.
Pyrethrins (Pyganic) are toxic to bees. They cannot be applied when the crop is in flower or when there are flowering weeds within the crop (e.g., dandelions and clover in the grass). After they are sprayed, the active ingredient will break down quickly leaving minimal residual effects on pollinators later on. There may be a good window for application after dandelions are done flowering, but this will depend on the site and the weeds present. Trounce contains a small amount of pyrethrins so it is best to follow similar guidelines for that product in lavender. Pyganic is OMRI listed and likely acceptable for organic production, but always check with your certifying body before applying any pest control products. Not all of the insecticidal soaps are OMRI listed, so check with your certifying body to ensure they are permitted for use if you are certified organic.
NOTE: Very few pest control products have been tested on lavender directly, so it is always important to test products on a few plants first and wait a day or two to confirm there is no phytotoxicity before applying them on a large scale.
Always read the full product label before applying any pest control product.
The following are key excerpts from the product labels:
Pyganic Crop Protection EC 1.4 II: Apply at a rate of 2.32 – 4.65 L/ha. Monitor for pest presence and apply when pests are first observed; do not wait until plants are heavily infested. Repeat application if necessary, as indicated by monitoring, but do not reapply within 3 days. Do not apply more than 10 times per year. Do not apply more than 46.5 L/ha (600 g ai/ha) per year. Apply in sufficient spray volume to ensure complete and thorough coverage of all plant surfaces. Restricted Entry Interval: 12 hr.
Safer’s Trounce: Mix fresh solution. Trounce insecticide is a fast-acting, short-lived product. When insects appear, spray all plant parts including upper and lower leaf surfaces. Insects must be sprayed directly to achieve proper control. Do not spray plants in direct sunlight. Make applications when weather conditions promote slow drying such as early morning, late afternoon to evening. The longer the spray solution remains in the liquid state, the longer the product remains active. Apply 5.0 L/ha of product/100 L of water, in a spray volume of 625 L/ha. Eight applications per crop season. Ground application only. Foliar application using conventional ground application equipment. Pre-harvest interval: 1 day; Restricted Entry Interval: none specified.
Opal and Kopa Insecticidal Soaps: Mix 8 L of product with 400 L of water. Add sufficient water to the mixing tank to allow proper agitation by pump or paddles. Continue stirring while adding first the Insecticidal Soap then the remaining water. Hard water in excess of 300 ppm should be conditioned to reduce its hardness prior to mixing with Insecticidal Soap. For field applications, apply the diluted solution at a rate of 700 to 1900 L/hectare using ground spray equipment. For best results commence treatment when infestation is first noticed. Thoroughly spray insect pests on plants with diluted product to wetting. Minimize run-off to reduce plant injury on sensitive plants. Insecticidal Soap is a contact spray and is effective in its liquid state. Pests need to be contacted with spray solution to be effective. Efforts should be made to thoroughly reach all plant parts including undersides of leaves. Repeat treatment every one to two weeks as needed. Apply to a maximum of three consecutive applications to ensure plant injury does not occur. Sensitivity varies with plant varieties. If concerned about sensitivity of plants, apply to individual plants or small areas of plants and wait to determine if plant damage (phytotoxicity) occurs before treating larger areas. May be used on edible crops up to and including day of harvest. Restricted entry interval: none specified.
All of these products are commercial products and growers will need their Grower Pesticide Safety Course Certificate in order to purchase them. To obtain your certificate, visit www.opep.ca.
