Eric Sideman's Pest Report
June 19th, 2000
This is the first pest update from me for the 2000 growing season. I have been buried in comments on the USDA's second proposal on organic farming. Now that MOFGA's comments are sent off to D.C. I can get to my real work.
First of all, I want to that my regular sources of information. I appreciate their willingness to allow me to take material from them. The helpful folks are: Ruth Hazzard and Sonia Schoelmann from U. Mass., Vern Grubinger from UVM and Dave Handley from U. Maine.
Also, I want to stress that you, our MOFGA certified organic growers, are the most up to date sources. Please send me any sightings or questions you have.
Crop Conditions
This season is starting off very slowly. My strawberries are going to ripen about 2 weeks later than last year. There has not been a great deal of rain but it has been cool and the ground has taken a long time to warm up and dry. Germination of warm weather crops such as squash has been very poor, especially in heavy soils. Transplanted warm weather crops that were not covered are growing very slowly.
Pests to note
Cutworms are particular active this year. I have seen bad damage in onions, carrots, beans. Bt will kill the critters if they eat it...that is the trick. The problem is that they do a lot of damage by the time they eat enough Bt to be effective. I have also experimented with a bait. Make a very concentrated solution of Bt and mix with wheat bran and some molasses. If you often have problems you may want to keep the fields plowed in the fall and spring. I hate seeing the bare ground, but if the moths have no place to lay their eggs -they lay eggs at the base of plants including weeds and the eggs hatch into the caterpillars- there will not be any cutworms. I like the Bt bait better.Flea beetles have been a problem for many. I suggest covering all early planted susceptible crops with a floating row cover. Of course it is too late for that. There is not much else you can do. Spraying with rotenone will kill a bunch of them but new ones will fly in again. Most crops will out grow the damage and recover fine.
Colorado potato beetle adults are laying eggs now. This is the time to pay attention. Flag a bunch of egg clusters (yellow bunches on the underside of the leaves) and when they hatch it is the time to spray the effective Bt strain (Novadore or CPB Beater, etc,). Spray again in about a week when the rest of the eggs hatch.
European corn borer flights have begun in Massachusetts. Keep your fields scouted. The first signs of corn borer damage are leaves unfolding from the whorl already with small holes in them. The borer is a caterpillar and so Bt (the strain for caterpillars such as Dipel) will work very well. Spray right over the top of the corn if you see significant damage. The IPM action threshold is to spray when leaves of 15 percent of the scouted plants in the pretassel stage show signs of fresh ECB feeding.
Striped cucumber beetle invaded newly emerged fields already. Remember, this beetle carries bacterial wilt and so the damage goes beyond the obvious feeding damage. Scout field regularly and control this pest with a good pyrethrum product, but only if you find damage. Spray early in the morning (I mean early!) before they become active. Otherwise they will fly away as you walk down the row. Remember, the botanicals or the Bts have no lasting protective effect. They both become inactive very quickly in sunlight so it only makes sense to spray when there is a susceptible pest present.
Strawberry clipper and strawberry root weevil have been quite bad in some fields this year. If you have a bad problem with either of these pests it is time to rotate out of the field soon after the picking season ends. Plow up the field and keep clean cultivated for 2-3 weeks before putting on the cover crop. This should encourage bird feeding on the larvae. At this time it is too late to spray any material for control.
(About the author: Eric is MOFGA’s "extension agent" and can be reached at the MOFGA office to answer your questions about farming and gardening. Link to MOFGA Contact Page, or email Eric directly.)