UConn Extension Vegetable IPM Pest Message & Reports from the Farm, Friday June 12, 2015

Transcription

1 UConn Extension Vegetable IPM Pest Message & Reports from the Farm, Friday June 12, 2015 [Comments or answers in brackets are provided by Jude Boucher, UConn Extension] There was a mistake in the message last week. The last four farms were from the first report of the previous year I had a computer (or mind) glitch which failed to delete those reports. Sorry about that! Steve Bengtson, Cold Spring Brook Farm, Berlin, CT ECB traps were set up on Sunday June 7. After 4 nights I found 2 moths in the NY (E) trap and 4 moths in the IA (Z) trap. For a total of 6 moths. Scouting the corn which ranged from tasseling to pretassel resulted in 0% to 2% infestation. I'm just beginning to see some silk in our earliest variety so I will set up my CEW traps as soon as possible. No sign of early blight yet in our early tomatoes. Peppers are growing well after receiving an injection of Zampro last week through the drip irrigation system to ward off Phytopthora. Deer are enjoying our early cucumber field. [Crop damage permits or an electric fence should stop damage.] Our early muskmelon field is showing some spotting on the leaves. Close inspection showed a minor infestation of thrips. I didn't find any information in the Vegetable Mgmt. Guide for thrips on muskmelon. If the problem persists do you have any suggestions on which chemicals might be effective? [The problem will probably not result in important or economic damage to the plants, that s why it doesn t appear in the Management Guide. If it does get worse Radiant with an adjuvant should bring the problem under control.] I found the first signs of powdery mildew on our early squash field today. The mildew showed up on the east side of the field near the fence line which shades the field in the morning. I will need to use a spray with 0 days to harvest as we are harvesting squash daily. Any suggestions? [Because summer squash is a short season crop, and powdery mildew starts first on senescing leaves, it is always the first crop to have PM, but usually only requires one or two fungicide applications to get you through harvest for a planting. Vivando, Torino and Procure are all zero days to harvest, but growers with a lot of full-season cucurbit crops like pumpkins and winter squash may want to save their single application of these mobile fungicides for when the disease show up on those crops. Protectants registered for summer squash may be a better choice on this first planting: Bravo-type products, Milstop, or Microthiol sulfur. Under leaf coverage is important when using protectants. Use sequential plantings to keep a good supply of SS coming and don t try to keep one planting alive for too long. It costs too much money to have your help search for fruit after 2-3 weeks. Till down old plantings after the last harvest to reduce sporulation and infection on later plantings.] I saw just a few leafhoppers in our eggplant today but not enough to spray yet. Some of the plants have raspy holes in the leaves. Picture below. Any idea what could be causing this? Cutworms? [The threshold for potato leafhopper sprays on eggplant is PLH per leaf.]

2 [These holes could be caused by any number of beetles: Colorado potato beetle, spotted cucumber beetle, three-lined potato beetle, Asiatic garden beetle, Japanese or Oriental beetles, or margined blister beetle. It is a little early for the last four mentioned, but the first three are out and active. Also, remember that flea beetle holes tend to enlarge as the leaves grow. This low amount of injury bears watching, but does not represent economic damage to the plant or warrant a spray at this time. ] Cecarelli Farm, Northford, CT [reported by JB] I m teaching Willy Dellacamera how to scout and monitor for sweet corn and tomato pests this season. In their earliest three corn fields we saw numerous European corn borer moths flying in the field and in the mating zone or tall weeds at the margins of the fields. The moths are in the field laying eggs at this time, but few larvae have hatched yet as we only found 2% of the plants infested at the late-whorl to pre-tassel stage, and no infestation in the younger second and third plantings. The percent infested plants will increase dramatically this coming week. You should start to scout pre-tassel stage plantings now and treat if more than 15% of the plants are infested with larvae. One of the things I m trying to check out at the UConn Research Farm this summer is if a single application of Coragen will control this pest completely. Our normal recommendation is to apply two sprays 3-5 days apart, because borer larvae ride the tassel up out of the whorls where they are exposed just before the tassel opens.

3 However, not all the plants mature at the same rate, so it usually takes a second application to get the ones on the tassels that emerge from the whorls a little later. No diseases were found on their tomatoes. Oxen Hill Farm, W. Suffield, CT [reported by JB] Eggplant in the same field as last year had an average of 2 Colorado potato beetle egg batches per plant. A newly rented field of potatoes about a mile away, that hadn t had solanaceous crops in it for 3 years, had no CPB adults or eggs. This demonstrates how important it is for growers, especially organic growers, to rotate your crops to a distant field, if possible. We usually think of crop rotation as a disease fighting technique, but it can be just as important for insects. By rotating to a field at least ¼ mile away many beetles perish while trying to migrate, and colonization of the new field will be later and lighter than in an unrotated field. This tool is as important for organic growers as Entrust insecticide. You should be aware that Dow threatened to withdraw the sales of Entrust from the Northeast this week because some growers have been abusing the product and using it exclusively on certain pests. Dow is afraid that if resistance to spinosad becomes common then cross-resistance to the closely related active ingredient in Radiant will soon follow. Rotating to a distant field is also very helpful for a number of important pests that have trouble migrating long distances, such as squash bugs, Mexican bean beetles, cabbage maggots, striped cucumber beetles, flea beetles, squash vine borers, etc. etc. Rotating doesn t work for pests with a lot of alternative hosts such as ECB, or for pests that migrate long distances such as potato leaf hoppers and corn earworms. If you farm in several isolated fields, try planting all of your solanaceous crops like tomatoes, potatoes, eggplant, peppers, tomatillos and husk tomatoes in one field, and all your cucurbit crops like squash, melons and pumpkins in another field, and all your Brassica crops in another, and a mix of miscellaneous vegetables in yet another. Then rotate all the crops to a new field the next year and you will find that you leave most of those chronic pests behind. George Hall Farm, W. Simsbury, CT [reported by JB] Same thing! The CPB eggs had hatched and infested all their solanaceous crops with between 30 and 100 larvae per plant. The only choice he has at this point is to use Entrust yet again for this generation of beetles. Next year he will rotate these crops to a field that he is not using Solanaceous crops for this year. At the edge of the same field was a planting of pak choy that had up to 100 flea beetles per plant. The Entrust will also control flea beetles pretty well, but they also need to be moved to a new site and maybe covered with a row cover. Dave Roston, Manager Farm Fields & Kitchen, Enfield Prison [reported by JB] It was a pleasure to work with the prisoners this week who were keenly interested in information about the pests that have been attacking their crops for the last couple of years. This site will be a particular challenge as the prison has a budget for lime, seed and fertilizer and not much else but boy do they have labor! They also had plenty of adult CPB and a few eggs in their potato field, so will start hand crushing. They also have access to row covers (go figure!) so they were going to cover the field the next

4 day and repeat the hand crushing exercise under the covers. Question: if prisoners are under cover and out of sight, is that a problem? Josh Vincent, Vincent Farm, W. Suffield, CT [reported by JB] CPB adults and eggs were present on his eggplant only. He will send his crew back in to hand crush a second time. With only 6 rows of eggplant hand crushing can be a practical method of fighting this pest even on a wholesale conventional farm. Diseases were absent from his tomatoes. ECB traps were set up in the action sites along the edge of his corn fields. His earliest two fields were scouted and both fields had only 2% of the plants infested with ECB larvae. This will change quickly in the next week or two as more eggs are deposited and hatch. One young sweet corn field had a thick population of weeds and he had already attempted to control them with cultivation. He will make a post-emergence application of herbicide to control these weeds. One of the best options would be to use Impact with methylated seed oil and liquid nitrogen (26-0-0) adjuvants. This will remove most small broadleaf weeds and crab grass. If the field had mostly nutsedge, as I have seen on a couple of farms this year, then the better choice would be to use Sandea post-emergence. These post emergence products must be applied before the weeds reach the specified height on the label to get a good kill and to prevent future resistance problems. Steve Munno, Massaro Community Farm, Woodbridge, CT [reported by JB] Most crops were well protected with row covers and high tunnels on this organic farm. The biggest problem is the building population of spinach leaf miners on the farm. Steve tried the Diglyphus parasitic wasp on the first generation without much success but expects delivery of another batch next week for use on the second generation of leaf miners. If you want to try using this biological control agent on your farm, try to order your wasps so that they arrive as eggs begin to hatch because they attack the very young larvae. Michaele Williams, Vegetable Crops Field Manager, Bishop s Orchard, Guilford, CT [reported by JB] Kale was scouted and had 10% of the plants infested with diamondback moth larvae. They expect to finish up harvesting this planting this week so a spray application will probably not be necessary. If you like to include a B.t. product in your insecticide rotation for Brassica crop caterpillars, remember that the B.t. aizawai strain that is in XenTari and Agree was specially formulated to work on DBM, and will also work well on imported cabbageworm the larvae of that white butterfly. The kurstaki strain that is in most B. t. products on the market will not control DBM as well as the aizawai strain. Roger and Isabelle Phillips, Sub Edge Farm, Farmington, CT [reported by JB] There were no CPB on their eggplant or potatoes yet. This may be a benefit of being a new vegetable farm. However, unlike most farms where I failed to find potato leaf hoppers this week, they had up to 2 per plant on their young snap bean planting. The threshold for this pest is 2 per foot of row for newly emerged bean plantings and 5 per foot of row from the seedling stage up until bloom. PLH can also be excluded with row covers up until bloom and later infestations after the covers are removed will not

5 affect yields. If PLH are already infesting your planting, you can remove them for 24 hours with PyGanic applied to the underside of the leaves, which will give you time to apply the row covers. Different varieties tolerate leafhopper feeding better than others. I am conducing a trial of all the Harris bean varieties this year at the research farm to see if we can start a list of tolerant varieties. Next year I ll drop the ones that are most susceptible and add some from another seed company. Conventional growers can use below-label-rates of dimethoate or use other insecticides listed in the management guide to protect plants for 7-10 days. That s enough for this week. I ll send you another update next Friday, June 19 th.