Pest & Crop Newsletter, Entomology Extension, Purdue University

Insects, Mites, and Nematodes

Soybean Aphid Numbers Back Down Again
Harvest Restrictions for Soybean Insecticides
Black Light Trap Catch Report

Weather Update

Soybean Aphid Numbers Back Down Again – (Christian Krupke)

After a spike in aphid numbers about 10 days ago, we are back down to single digits aphids/plant in most areas. At this point it is highly unlikely that aphids will make a 2006 “run” and build the populations sufficient to necessitate treatment. It is useful to note that although we had aphid numbers in the low to mid 100’s/plant in some fields, followed by favorable “aphid weather” (temperatures in the 80’s, low relative humidity) we did not have any of these fields reach threshold. This is an example of the importance of scouting when it comes to these pests, and of the folly of “spraying early.” Growth curves of soybean aphid populations are difficult, if not impossible, to predict and the best bet is sticking to weekly counts and treating only at threshold. We will have another update on soybean aphid numbers later this month.

Harvest Restrictions for Soybean Insecticides - (John Obermeyer and Christian Krupke)

Severe woollybear caterpillar feeding.

Fortunately soybean aphid has not developed as much of a threat this year. However, defoliating insects such as bean leaf beetle, woollybear caterpillars, or grasshopper may be on the rise in some fields. The following listing includes some of the many insecticides registered for soybean insect control, including rate per acre and harvest restrictions. Refer to the label for insects controlled and specific rates and application information.

Product	Rate and Formulation	Days Before Harvest
carbaryl (Sevin)	2/3 lb. 80WSP 1-2 pt. 4F, XLR+	21 21
chlorpyrifos (Lorsban)*	1pt. 4E	28
cyfluthrin (Baythroid 2)*	1.6-2.8 oz. 2EC	45
deltamethrin (Delta Gold)*	1.5-1.9 fl. oz. 1.5EC	21
dimethoate (Dimethoate)	1 pt. 400, 4EC	21
esfenvalerate (Asana XL)*	5.8-9.6 oz. 0.66EC	21
gamma-cyhlothrin (Proaxis)*	1.9-3.2 oz. 0.5EC	45
lambda-cyhalothrin (Warrior)*	1.9-3.2 oz. 1CS	30
permethrin (Ambush)* (Pounce)*	3.2-6.4 oz. 2EC 2-4 oz. 3.2EC	60 60
zeta-cypermethrin (Mustang Max)*	2.8-4.0 oz. 1.5EW	21
*Restricted Use Pesticide

Click for Table.
Black Light Catch Report.

Temperatures as of August 16, 2006

DISCLAIMER: Reference to products in this publication is not intended to be an endorsement to the exclusion of others which may be similar. Persons using such products assume responsibility for their use in accordance with current directions of the manufacturer. It is the policy of the Purdue University Cooperative Extension Service, David C. Petritz, Director, that all persons shall have equal opportunity and access to the programs and facilities without regard to race, color, sex, religion, national origin, age, marital status, parental status, sexual orientation, or disability. Purdue University is an Affirmative Action employer.