Extension Report

Baldwin County Extension Office

302A Byrne Street

Bay Minette, AL  36507

Telephone (251) 937-7176 or

928-0860/943-5061 ext. 2222

FAX (251) 937-7285

Ayanava Majumdar

Extension Entomologist

Peanuts & Vegetables

June 22, 2010

Updates on Insect Pest Activity and Control Recommendations

Integrated pest management or IPM is a smart way of managing insects for maximizing profitability. IPM starts with the timely detection of insect pest and ends with timely intervention of key pests using multiple tactics. Below is some research-based information that can help readers understand insect pest population dynamics and note some changes in insecticidal recommendations. There have been several reports on increasing insect activity on vegetables and field crops. This report has been prepared on the basis of direct crop scouting and insect trapping information gathered from various parts of Alabama. Residents in counties around the Gulf of Mexico (Baldwin and Mobile Counties) should immediately scout their crop in order to detect a pest problem. Current research with insect attractants has indicated high activity of armyworms, corn earworm, and lesser cornstalk borers across Alabama. Beet armyworms have been observed in high numbers (48 moths per trap) in Baldwin County along with a slowly rising population of Fall armyworms. The Fall armyworm is a very devastating insect pest of grasses and vegetables; it completes several generations each year in the south resulting in pockets of high population pressure. Due to the strong attraction of armyworms to grasses, hay producers should watch for insect populations (outbreaks already reported). Corn earworm or tomato fruitworm is also active in many crops and trap catches in Baldwin County have reached 19 moths per trap. Caterpillars have been observed devouring green tomatoes in untreated vegetable research plots in Baldwin County. Note that the tomato fruitworm larvae feed with their head inside the fruit while the rest of the body remains outside. Tobacco budworm, a closely related species to the tomato fruitworm, has not been found in traps yet but that does not mean caterpillars are not active. Caterpillars of the tobacco budworm and the tomato fruitworm look alike in early stages; commercial crop producers should bring samples to the nearest County Extension Office for correct identification before applying costly insecticides to avoid mistakes. Lesser cornstalk borer is a soil pest that was present in very high numbers in 2009 (over 100 moths per trap); the flight of these small moths remained high throughout the season last year indicating the need for vigilance against this pest in 2010. Current lesser cornstalk borer number from Baldwin County is 57 moths per trap and it is anticipated to go up rapidly if high temperatures and dry conditions persist in the region. Crop producers and gardeners are encouraged to monitor insect activity using pheromone and colored traps followed by detailed examination of crop canopy and soil samples. Rescue treatments with liquid insecticides generally fail to control the lesser cornstalk borers because insecticides may not penetrate the silken tunnels that protect grubs in soil. Planting-time soil insecticide (e.g., chlorpyrifos) is recommended for cornstalk borer control in peanuts. Other insect pest issues reported in Alabama include the sugarcane beetle, stink bugs, and aphids. Sugarcane beetle is a medium-sized black insect with hard exocuticle and oar-shaped legs with numerous spines. This insect was reported from a few north central counties in Alabama last year (2009); however, in 2010, specimens have been collected from corn fields in north Alabama to the Gulf Coast. Sweet corn producers should get in touch with a Regional Extension Agent if they suspect this insect to be causing crop lodging (look for randomly cut corn stalks and dig around soil cracks at base of plant). Green peach aphid and potato aphid are abundant on vegetable crops; rapidly multiplying population of aphids can cause severe crop injury within few days. Many species of stink bugs and leaffooted bugs are actively feeding on green tomatoes; homeowners do not have very good chemical control products for stink bug management but readers are encouraged to plant vigorous varieties and use trap crops to reduce damage to the main crop. If you wish to stay updated about these and other insect pest outbreaks throughout the summer season, then please subscribe to the weekly electronic newsletter called “THE IPM COMMUNICATOR” by emailing bugdoctor@auburn.edu. Past issues of this newsletter are available at www.aces.edu/go/128.

Proper Use of Insecticides in Backyard Vegetable Garden

For a detailed description of insecticides for home garden vegetable production, readers should check previous newspaper articles published by this author in January and April. It is interesting to witness the availability of systemic insecticides for backyard vegetable production. Commercial vegetable producers have been using imidacloprid-containing insecticides for some time. Imidacloprid is a systemic insecticide with LD50 of over 5,000 mg/kg with good activity against many sucking insect pests and some beetles. Until 2010, systemic insecticides (e.g., imidacloprid) for home garden use were largely restricted for use on trees and shrubs (e.g., Bonide’s Tree & Shrub Insect Control, Bayer Advanced Merit Tree & Shrub Insect Control, Ferti-Lome Tree & Shrub Systemic Insecticide Drench, etc.). Concentration of imidacloprid in tree, shrub and lawn insecticides ranges from 0.2 to 1.5% approximately. Recently, Bayer Advanced has introduced the Fruit, Citrus and Vegetable Insect Control Concentrate (or Bayer FCV) with a broad activity label; this new product has 0.24% imidacloprid. Do not get confused with another chemical called acetamiprid which can be found in many ornamental insect control aisle at superstores; acetamiprid is not labeled for home garden vegetable production. Bayer FCV (imidacloprid) should be used as a drench near the base of plants soon after transplant. In small research plots at the Gulf Coast Research and Extension Center, imidacloprid was applied around the base of plants about 10 days after transplanting tomatoes, okra and bell peppers. The application of imidacloprid in test plots was triggered by the presence of winged aphids and whiteflies on plants in early May. Imidacloprid is absorbed through the root system within 3-4 days of application and the protection lasts about three weeks. As an early season insecticide, imidacloprid can benefit in plant establishment by reducing stresses. The effect of imidacloprid in test plots was most noticeable on young okra plants (see picture) and bell peppers, and least visible on tomatoes due to their extensive foliage. Note that the pre-harvest interval for Bayer FCV is 21 days which means you have to apply the product timely to avoid eating contaminated produce. Do NOT spray imidacloprid on leaves or fruits as a rescue treatment later in the season. Bayer FCV can only be applied once per season on garden vegetables. After the effect of imidacloprid wears off, home owners can maintain insect free crops using a good rotation of contact insecticides like carbaryl, malathion, and softer insecticides (e.g., insecticidal soap, horticultural oils, neem, or Dipel). Do not use chemicals if plant damage is below the action threshold. Gardeners can use carbaryl and malathion as spot treatment insecticides to reduce impact on beneficial insects. While spraying insecticides, reverse the spray nozzle of hand-held tank sprayers to reach to the underside of leaves because insecticides applied to the top will lose efficacy very rapidly from sunlight plus some insects like leafhoppers and stink bugs will try to hide under the leaf as you spray. Always read the insecticide label before you apply any product.

For additional questions, contact your County Extension office at 937-7176.

Email address: azm0024@auburn.edu

Phone: 937-7176 or 943-5061, ext. 2222

The Alabama Cooperative Extension System (Alabama A&M and Auburn Universities) in cooperation with the U.S. Department of Agriculture is an equal opportunity educator and employer.