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| Vegetable Crop Advisory Team Alert newsletter | |||||||||||||||||
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| Vol. 22, No. 8, June 13, 2007 |
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In this issue European corn borer update Corn earworm/tomato fruitworm found in traps Downy mildew reported on cucumbers growing in Canadian greenhouses Are your asparagus transplants turning white? How effective is your irrigation system?- Field day on June 27 Regional reports Weather |
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European corn borer update The numbers of European corn borer moths caught in pheromone traps were down last week, compared with the previous week, at all locations in Michigan (see Table). However, degree-day totals (base 50) indicate that moths are still laying eggs (consult degree day table in this issue of the Vegetable CAT Alers or visit MSU’s Enviroweather at http://www.enviroweather.msu.edu). In some sweet corn fields, heavy infestations of corn borer larvae are reported feeding in the whorls. Insecticide treatment may be required if 20 percent or more of whorl-stage corn shows evidence of feeding. Treat corn four days or less before tassel emergence to prevent corn borer larvae from entering the developing ears. Consult Bulletin E-312, 2007 Insect, disease and nematode control for commercial vegetables insecticides registered for control of European corn borer in sweet corn. You can find this bulletin online at http://web4.msue.msu.edu/veginfo/E312. European corn borer moths caught in pheromone traps in different Michigan locations from June 6 to June 12
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Corn earworm/tomato fruitworm found in traps A few corn earworm moths were caught in pheromone traps in Ingham County. These probably migrated into the area on the weather front last Thursday, June 7. Sweet corn is not vulnerable to corn earworms until green silks are present. However, corn earworms also lay eggs on tomatoes and larvae (which are also known as tomato fruitworm) feed on developing fruit. It is unlikely that large populations of corn earworm moths are present in Michigan, and weather patterns for the foreseeable future are not conducive to more migration. However, we have occasionally had tomato fruitworm infestations in June. Growers should check tomato fields for eggs and fruit feeding. Eggs are greenish-white and laid singly on the upper or lower surface of leaves. Larvae vary in color from light green to reddish brown and bore into green tomato fruit soon after hatching. If necessary, insecticides must target the newly-hatched larvae, since once inside the fruit, larvae are protected from insecticides. |
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| Downy mildew reported on cucumbers growing in Canadian greenhouses Downy mildew has been confirmed on greenhouse cucumbers in Essex County in Canada. These are not plug plants for field production but are “hothouse” cucumbers. Essex County is Canada’s southernmost county located on a peninsula of land that juts out into the region of the Midwestern United States. At this time, no field outbreaks have been reported in Canada or Michigan. The greenhouse outbreak in Canada is troubling news for Michigan pickle and cucumber growers. The field cucumber growers in Canada are better equipped to handle downy mildew than they were a year ago because of expanded fungicide labels. However, I don’t think that Michigan growers can assume that downy mildew will stay in Canada. The recent dry and bright sunny weather will delay downy mildew development in Canada, for now. My concern is that the downy mildew spores will leave the greenhouse and infect nearby field plantings of cucumbers. If a field of cucumbers becomes infected in Canada, then our risk in Michigan increases. The vegetable crop specialist in Canada is recommending that field cucumber growers in Canada spray preventively. It is my opinion that cucumber growers in Southeastern Michigan should spray fields preventively now. If the growers in the areas of the Midwest closest to Essex County spray diligently, perhaps a 2007 epidemic can be averted. Spore trapping for downy mildew in Michigan began last week with some stations still to be set up this week. Sprays can be banded for fields that are young and newly emerged. Cucumbers that have been growing under tunnels will be larger and will need to be covered completely with spray to be protected. A spray interval of 10 days is currently recommended. The following fungicides are recommended:
Alternate these products and mix each with either mancozeb or chlorothalonil (i.e. Bravo). This development will be watched carefully and new information and recommendations posted. |
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| Are your asparagus transplants turning white? In the near future, most large scale asparagus growers will continue to establish new production fields from one-year-old crowns. However, there has been some interest in experimenting with greenhouse-grown transplants as alternative planting material, at least on a small scale. Asparagus establishment from greenhouse-grown transplants is not new, but has not been widely used by Michigan growers for several legitimate reasons. Those interested in plug production have reported that transplants were turning white in the greenhouse and were wondering if there was a problem with those transplants. We have observed this problem in our greenhouse trials. In our trials, white ferns occurred first in trays with smaller cells and last in trays with the larger cell volume. Some growers have indicated that increasing the amount of fertilizer did not solve the problem, which was also the case in our tests. The light environment and nutritional status of the plant may play a role in this problem, but this usually occurs when the root system has occupied most of the cell volume. Under these conditions, the cell volume becomes a limiting factor in the growth of the transplant. That is probably the reason why adding more fertilizer does not solve the problem. If the ferns on your asparagus transplants are turning white despite adequate fertilization and lighting schedules, that is probably a good indication that they should be hardened off and transplanted. New green ferns will develop once the transplant is well established in the field. |
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| How effective is your irrigation system?- Field day on June 27 Learn how to check your irrigation system with MSU Extension educators. An irrigation system field day will be offered Wednesday, June 27. This event will be held at three different locations and times for your convenience. Bosch’s Countryview nursery at 10:00 AM, Woodland Enterprises Blueberry Farm at 1:00 PM and Victory Farms at 3:30 PM. Please view attached flyer or PDF for exact locations. The event will cost $5.00, and the registration deadline is Monday, June 25. You may pay at workshop. Please contact MSU Extension-Otttawa County for more information at 616-846-8250. Dr. Tom Fernandez, Department of Horticulture, will be demonstrating the techniques you can use to do your own system checks. |
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| Regional reports 1 -- Southwest Ron Goldy Weather Temperatures during the week ranged from highs of 70 oF to 89oF and lows from 40oF to 65oF. The area received no precipitation. Transplanting conditions have been excellent provided irrigation is available. Crop reports In general, there are few disease and insect problems to report. The biggest concern is keeping up with irrigation needs. Tomato, pepper and eggplant transplanting, staking and tying continue. Early, non-tunnel-grown tomatoes and peppers are at bloom and early fruit set. Tunnels are being removed from tunnel-grown plantings. Early planted peppers are producing secondary branches. Watermelon and cantaloupe are beginning to runner off the plastic. Cucumbers have responded well to warm temperatures and those grown under tunnels have 4 to 6 inch fruit. Harvest will probably begin next week. Early, non-tunneled plantings of cucumbers and squash are at early fruit set. Still no reports of cucumber beetles at this time. Zucchini and yellow squash harvest will begin soon from tunnel-grown plants. Sweet corn growth is at 14 to 16-inches. Early potatoes are in full bloom. Colorado potato beetle adults are active and eggs can be found. |
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| 2 -- Grand Rapids Area Bill Steenwyk Weather Warm, windy and dry are the terms that sum up our crop growth environment this past week. Rainfall was negligible, with Hudsonville receiving 0.13 inch on June 7, but most of the area received only a few hundredths, if any at all. High winds and warm temperatures combined to draw 2.0 to 2.5 inches of water from the soil. For dryland producers, the deficit will become serious soon. Crop reports The present condition of most of our crops, remains quite good. On muck soils in Van Buren, Allegan and Ottawa counties, celery, onions, red beets, radish and leek crops are healthy, except for a few situations where thrips or yellow nutsedge is hampering growth. Many of the onions are setting bulbs. On upland soils, tomatoes are in bloom and look good. Cabbage continues its vigorous growth, with only minor feeding from diamondback moth and imported cabbage worm larvae. Peppers, squash and most other crops are progressing well. Where irrigation is not sufficient, water availability, especially on coarse-textured soils, will soon begin to limit yield. Growers should continue to watch for weed outbreaks. With the current dry conditions, yield loss from competition can be substantial. I continue to find Stewart's bacterial wilt in Kent County sweet corn fields. So far, the fields most affected were planted with Stewart's wilt-tolerant varieties, using seed treated with an insecticide labeled to control the flea beetles which spread the pathogen. Growers who intend to plant more sweet corn should take every precaution to avoid this yield-robbing condition. Only three European corn borer moths were caught in the pheromone traps. |
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| 3 -- Oceana County Norm Myers Weather We’ve had a very hot, dry week. The front that came through last Thursday, June 7 and Friday, June 8, dumped very little rain, but the high winds associated with it sandblasted a lot of crops in our area. Most growers are struggling to ramp up their irrigation systems ahead of the very hot, very humid weather predicted by this weekend. Crop reports Much of the asparagus that was through the ground last Thursday, curled enough from the sand damage that it was only good for cuts and tips. Weeds, especially pigweed, are really coming on now, so most growers are planning to use a burn down herbicide with their post-harvest herbicide application. Most growers are still harvesting, but the predicted heat this weekend will probably finish off production in a lot of fields, even though the fresh and processed markets are both screaming for more asparagus. Growers with irrigation available are planning to use it on both newly planted and established fields. Those that used irrigation during the hot, dry June of 2005 feel that it helped their asparagus for several years after, because it allowed it to put up healthier fern than it would otherwise have done, even though the growers picked later than most of their neighbors. In carrots, sandy spots in many fields, especially the latest plantings, eroded pretty severely. Scouts report that there are still a few globular springtails around, and aster leafhopper numbers are beginning to rise. Winter squash and pumpkins are mostly emerged and forming true leaves. Some of those fields were beat up pretty badly by last Thursday’s wind. It has been pretty dry since planting, so I am anticipating that our herbicides will probably not work well. Our soybean aphid trap in Mason County has not caught any soybean aphid, even though they have been found in the other Michigan traps. In zucchini, most of the first planting of the processing and fresh fields have been planted. Some very early processing zucchini is emerged. One of my fresh market sweet corn growers is also reporting large amounts of Stewart’s wilt even on “tolerant” varieties. My European corn borer traps were empty this week. Perhaps it is too dry. |
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| 4 -- Mason-Newaygo counties Jim Breinling Weather The weather event of interest during the past week was the strong sustained winds that occurred on Thursday, June 7. Temperatures in the high 80’s were also recorded on that day at the Fremont and Ludington MAWN stations. The front that moved through the Ludington area about 1:00 AM Friday morning resulted in 0.76 inch of rainfall at the Ludington MAWN station. Rainfall amounts north of Ludington in Mason County were reported to be from 1.0 to 1.5 inches. To the south and east rainfall amounts were less with only 0.01 inch at the Fremont MAWN station in Newaygo County. Crop reports Some isolated wind damage was observed in carrot fields in Mason County. Early plantings are now at 6th leaf stage. Some isolated weed control problems also occurring. Snap bean plantings at a European corn borer site in Mason County, are now at 1st trifoliate leaf stage. There is some leaf damage, but wind damage appears to be minimal. Trap counts on Tuesday, June 12 were 0 – 0 – 0. Winter squash plantings in Newaygo and Mason counties are at 2 true leaf stage. Although leaves are battered in some parts of fields, plant loss appears to be minimal. |
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| 5 -- Macomb, St. Clair and Lapeer counties Hannah Stevens Weather and crop conditions Sunny, windy and dry characterize the weather this week throughout the region. High temperatures have ranged from 69oF one week ago to 91oF this Thursday, June 14. High temperatures were followed by windy conditions on Friday that caused some damage to young plants and probably brought in some migratory insects. While Macomb County (Romeo site) has the highest precipitation total in the state at this time, high evapotranspiration rates are drying soils quickly. Surrounding areas to the north have not had the rainfall, and some soils are very dry. Very warm air and soil temperatures have likely led to a couple reports of unusual post emergence herbicide injury symptoms to young plants. Crop reports In sweet corn, European corn borer flight is down this week, reflected by an average trap catch of 13.3 down from 48.3 last week. A sharp grower noticed a little feeding damage on his oldest corn. Except for plasticulture corn, which is robust, knee-high and tillering, it seems unlikely that corn at this time will be vulnerable to ear damage. Will tassels be emerging in four days? Check your fields. On muck soils most barley cover crops are now burned down, and fields are taking on their colors. Onions are being cultivated, and the crop stands appear to be uniform. Some early onion maggot has been reported. Romaine lettuce harvest got underway on June 10. Carrot stands look good as well with some scattered herbicide burn reported to foliage. Radish harvest is well underway. Garlic for retail sales are beginning to send up scapes, which are being removed. Pumpkins and hard squash seedings are emerging. Summer squash is beginning to flower, and harvest may be two to three weeks away. In melons, row covers are coming off as plants are beginning to run and flower. Female flowers with their tiny fruit are easy to find but male flowers, particularly those of the seedless watermelon pollinizers, are not in abundance yet. Cool season crops such as greens, chard, beets and others that survived two to three frost events are coming around. |
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| 6 -- Monroe County Paul Marks Weather No rain during the last seven days, combined with warm temperatures and low humidity, has dried our soils very quickly. Potential evapotranspiration as calculated from the Michigan Automated Weather Network station at Petersburg for these last seven days, now totals 2.21 inches, an average of 0.32 inches per day! This has created a need for irrigation systems to be restarted in many fields, especially where vegetation has now grown to nearly cover the soil. Crop reports Sweet corn is now showing tassels in many early plantings without any mulch or tunnels. Corn borer counts this week dropped to an average of just under four compared with 23 last week. Fields are heavily infested with very small larvae. Some Stewart’s wilt is now showing up in larger corn, some of which is tasseling. Earliest tomatoes for market now have fruits two inches and larger present with later plantings in open fields just beginning to blossom. Processing tomatoes are basically done being planted with earliest fields now having twin rows filled. No disease seen in this crop. Potato fields in all stages of growth have leafhoppers above threshold, even later planted fields which have not totally emerged. No potato beetles seen and no diseases seen in this crop. Pumpkin planting is nearly done with this string of very cooperative weather. Earliest fields have emerged. Cucumbers for slicers and for pickles have made very good growth this last week. Pickles are at the first true leaves, while slicers are in all stages from first harvest in tunneled plantings to emergence in later plantings. No downy mildew found so far this season. Cucumber beetle pressure is very low so far. Cabbage harvest has begun. Diamondback and imported cabbage worm larvae pressure has remained low. I have not found any thrips in this crop yet, but suspect with the warmer weather, and maturing small grains and grasses, it won’t be long. Peppers have made very good growth this week. First flowers are now showing in earliest fields. No aphids found in this crop, so far. |
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| Weather news Jeff Andresen Agricultural Meteorology Geography A strong upper air ridge and associated surface high pressure across the central United States will make for a very straightforward forecast for much of the remainder of the work week, with fair, warm and dry weather expected to continue. A weak cool front will move into the state from the north on Saturday, June 16, but given very limited moisture ahead of it only a few scattered showers are expected (mainly in eastern and northern sections of the state). Otherwise, dry conditions are a good bet across most locations through this Sunday. Temperatures will remain at slightly above normal levels, with highs ranging from the upper 70's in northern lakeshore areas to the upper 80's south and lows falling into the mid 50's north to mid 60's south. An upper air trough and associated cool front are expected to move into the region by the middle of next week, which will likely be the next chance for significant precipitation. Best guess at this point is the chance of showers and thunderstorms again in western sections of the state Monday and statewide on Tuesday. Following the movement of the troughing feature through the region next week, current medium range forecast guidance for the 6-10 day and 8-14 day time frames covering June 18-22 and June 20-26 respectively, suggests that the troughing pattern mentioned above will linger for much of the latter part of next week, resulting in a cooler and more unsettled weather pattern. The official NOAA 6‑10 day outlook calls for temperatures to range from near normal in eastern sections of the state to below normal in the west, and for precipitation totals to increase to above normal levels statewide. During the 8-14 day period, temperatures are expected to fall back to below normal levels statewide, with near normal precipitation levels. |
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