Rick Foster

Department of ​Entomology
Area(s) of Interest: Pest Mgmt. Vegetable and Fruit Crops
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Figure 1. Seedcorn maggot in a melon stem

I received my first report of seedcorn maggot damage on cantaloupes last week (Figure 1 and 2). A grower in northern Indiana reported losing 90-95% of his plants. Given the cool, wet growing conditions, it wouldn’t be surprising to see more reports of this type for a number of crops, including melons, beans, corn, onions, and crucifers. Some of these crops have insecticide alternatives that can be used at planting but other, like melons, have no such option. The best approach for melon growers is to either wait for warmer weather or cover the young plants with row covers to physically exclude the flies from laying eggs. If you have had plants killed by maggots, wait at least 3 days before replanting in the same holes to give the maggots time to complete their development. See the article from Issue 625 (published on April 13, 2017) for more details.

Figure 1. Black cutworm larva (photo by John Obermeyer)

We have had substantial black cutworm moth (Figure 1.) catches in our pheromone traps. Black cutworm moths typically lay their eggs on winter annual weeds growing in un-tilled fields. When the eggs hatch, the larvae will begin feeding on the weeds. Then, when you kill the weeds with either tillage or a burndown herbicide, the larvae are left there with nothing to eat. If you wait a couple of weeks to plant, they will probably starve to death. If you plant sooner than that, they will just be really hungry and will readily attack a variety of crops. The pyrethroid insecticides provide good, economical control.  

Many of our vegetable crops are attacked by one or more species of flea beetles (Figure 1). All species do similar types of damage, chewing small holes in the leaves. Damage is most important on young plants or transplants, so growers should watch young plants carefully. Fortunately, flea beetles are easy to control. Sevin®, the pyrethroids, and many other products will provide excellent control.

Crucifers such as cabbage, cauliflower, and broccoli are frequently attacked by a variety of caterpillars, with the most important being the imported cabbageworm, diamondback moth, and cabbage looper. The first caterpillar pest to attack crucifers is the imported cabbageworm. The adult stage is the common white butterfly that you will see flying around your field (Figure 1.). They lay eggs singly on the leaves. The larvae are velvety green and move very slowly (Figure 2.). They will consume large amounts of plant tissue and will also contaminate the heads with their feces. Your first indication of activity is when you see the daytime flying butterflies in your field. Once the butterflies are observed, you should begin watching your plants for signs of damage. Plants can tolerate a considerable amount of feeding damage on the leaves before heads begin to form. See the table on page 101 of the Midwest Vegetable[Read More…]

Figure 1. Armyworm damage corn leaves.

We have had major flights of armyworm moths (Figure 1.), as evidenced by pheromone trap catches. Catches have been highest in the northeastern portion of the state. Armyworms prefer grasses but will feed on other crops if necessary. During outbreak years, the infestation usually will start in pastures or other grassy areas. Once the armyworms have consumed most of the available leaf tissue, the larvae will march as a group (hence the name) looking for something else to eat. The next crop consumed may be wheat or early corn. When populations are heavy, the damage can be devastating. Fortunately, these kinds of outbreaks occur quite rarely. The last major outbreak we experienced was in 2001. If you have early-planted sweet corn, it would be wise to watch grassy areas for armyworm damage. If you see evidence of a problem there, watch your sweet corn for any signs of activity. The[Read More…]

Another update has been added for the Midwest Vegetable Production Guide for Commercial Growers 2017.   Under Root maggot controls for rutabagas, please substitute the information below for the existing information on page 211. Lorsban 15G at 3.3 fl. oz per 1000 linear ft. of row at planting or Lorsban 4E/Advanced at 1 fl. oz/1000 linear ft. of row at planting.

Growers that purchase the insecticide Belay® should read the label carefully. The new label will contain several significant changes. Please see this announcement recently released by Valent. “Valent is voluntarily removing or limiting certain crop uses on the Belay® label going forward due to on-going regulatory challenges with these uses. Specifically, all Fruiting Vegetable uses have been removed and uses for Cucurbits, and Potato have been modified. These changes have been made to both the Federal and State labels.  Valent is currently out of any old Belay® labeled product and will not be producing any additional material with that label. We are currently in production of Belay® with the new label and it should be available by mid-April. Customer owned inventory with the old Belay® label can be sold to growers and used by them going forward (no expiration period has been imposed).”

One way insects communicate with individuals of the same species is with pheromones. Pheromones are volatile chemicals released by an insect that usually can be detected only by individuals of the same species. There are a number of different types of pheromones, but the most common type is the sex pheromone. Usually the females will emit a tiny amount of a chemical that attracts the male to her and increases the likelihood of mating. Because the chemical is volatile, air currents carry it. The male detects the pheromone in the air with receptors on his antennae.  He then flies upwind to find the source of the pheromone, a prospective mate. The chemical compositions of pheromones for a number of pest species have been identified and synthetic copies can be produced in the laboratory. Synthetic pheromones can be used in conjunction with traps to catch male insects. Listed below are some,[Read More…]

Three species of seed and root maggots attack vegetables in Indiana. The seedcorn maggot feeds on seeds and seedlings of sweet corn, cucurbits, lima and snap beans, peas, and other crops. Cabbage maggots can cause serious damage to transplants of cabbage, broccoli, cauliflower, and Brussels sprouts and make the fleshy roots of radishes, turnips, and rutabagas unmarketable. Onion maggots are pests of seedling onions, developing bulbs and onions intended for storage. Seedcorn maggot flies (Figure 1) emerge in April and May and lay eggs preferentially in areas with decaying organic matter. Fields that are heavily manured or planted to a cover crop are more likely to have seedcorn maggot injury. Maggots burrow into the seed and feed within, often destroying the germ. The seeds fail to germinate and plants do not emerge from the soil, leaving gaps in the stand. When infested seeds germinate, the seedlings are weak and may[Read More…]

We just completed a new publication that will assist fruit and vegetable growers in protecting pollinators while still managing their insect pests. The title is “Protecting Pollinators in Fruit and Vegetable Production.” It can be found at https://extension.entm.purdue.edu/publications/POL-2/POL-2.html. There are two companion publications in this series, “Protecting Pollinators in Home Lawns and Landscapes” and “Protecting Pollinators: Tips for Commercial Agricultural Pesticide Applicators.” Additional publications in this series will target agronomic crop producers, folks who want to plant a pollinator garden, and how youth can help to protect pollinators.