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| Vegetable Crop Advisory Team Alert newsletter | ||||
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| Vol. 22, No. 2, May 2, 2007 |
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In this issue Early season insect pests: The maggots Prowl H2O and Outlook labeled for vegetable crops Dual Magnum 24C label for vegetable crops Disease management begins in the greenhouse Minimize the risk of frost damage when shooting for earliness Application technology for small acreage producers Regional Reports Weather news |
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| Early season insect pests: The maggots Beth Bishop Entomology Early season maggot flies (onion, cabbage and seed corn) are active and laying eggs. (view images) These insects are adapted to cool weather; they are more of a problem early in the season. Adult flies look similar to small houseflies. They are very mobile and do not spend much time in the field. Control methods should be directed toward protecting seeds, seedlings and young plants. Seed corn maggots feed on a variety of vegetable crops, including corn, beans and vine crops. They are the most cold tolerant of the three maggot species and, therefore, appear earliest in the season. Seed corn maggots cause more problems during extended periods of cool, wet weather, in soils with high organic matter, and when green manure has been recently incorporated. Simply delaying planting until the soil warms, and waiting a week or so after turning over green manure, will reduce damage. Planting insecticide-treated seed will also control seed corn maggot. Cabbage maggot flies lay eggs at the base of young cole crops. Adult cabbage flies first become active and lay eggs in the spring about the time yellow rockets bloom. The next generation of flies begins to lay eggs about the time daylilies bloom. Damage can be reduced if growers are able to wait until the soil warms in the spring to plant and avoid planting during peak egg-laying periods. Insecticide treatments at planting or transplanting will also reduce injury. See MSUE Bulletin E-312: 2007 Insect, Disease and Nematode Control for Commercial Vegetables for insecticides registered for control of cabbage maggot on different crops. Onion maggot flies lay eggs at the base of onion plants. Upon hatching the small maggots feed on the plant roots, causing wilting and seedling death. The first generation of maggots cause the most damage. Rotating fields and eliminating cull piles (in which onion maggots overwinter) can reduce onion maggot populations. Using treated seed (Trigard), or applying Lorsban at planting will protect young onion plants. Both Lorsban 15G and Lorsban 4E is registered as an at-plant treatment for onion maggot. In addition, Lorsban 4E can be used as a post-planting drench spray, although drench treatments are not as effective as at-plant treatments for control of onion maggot. See MSUE Bulletin E-312: 2007 Insect, Disease and Nematode Control for Commercial Vegetables. The at-plant treatment for Lorsban 4E was inadvertently left out of this bulletin—the rate is 1.1 fl oz/ 1,000 row feet (based on 18 inch row spacing--see label for directions). |
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| Prowl H2O and Outlook labeled for vegetable crops Bernard Zandstra Horticulture Prowl H2O was recently labeled for use on carrots, peppers, tomatoes and strawberries. The labels are supplemental labels, which expire at the end of 2008. Hopefully, they will be incorporated into the Section 3 label before that date, and become part of the permanent label. For carrots, apply up to 2 pints per acre (0.95 lb active ingredient ai) of Prowl H2O within 2 days of seeding. Prowl H2O needs to be watered into the soil with rain or irrigation to be effective. Prowl H2O may reduce stand of interplanted barley, so broadcast and cover the barley seed 10-14 days before planting carrots and applying the Prowl H2O. Prowl H2O can be used effectively in a tank mix with Lorox. It will improve control of annual grasses and some broadleaves, including common purslane and Lorox-resistant pigweeds. Observe a 60 day pre-harvest interval (PHI). For peppers and tomatoes, apply 1-3 pints (0.45-1.43 lb ai) per acre either pre-plant incorporated, pre-transplant or as a post-transplant directed application. Do not apply over the top of newly set transplants. Do not use Prowl H2O under plastic. Prowl H2O needs to be watered in to be effective. Observe a 70 day PHI. Prowl H2O gives good control of most annual grasses and broadleaves. It is weak on nightshades and does not control yellow nutsedge. It is most effective if used in combination with Sencor pre-emergence. For strawberries, apply 1.5-3 pt of Prowl H2O to the soil surface before transplanting. A second application may be made as a directed spray between rows. Do not exceed 3 pt per application and 6 pt per acre per year. Observe a 35 day PHI. Prowl H2O may cause stunting in strawberry plants, so avoid contact with the plants. The label does not include application on established strawberry. Outlook has been labeled for use on green onions. Apply up to 21 fl oz (0.98 lb ai) per acre after the green onions are in the second true leaf stage. Observe a 30 day PHI. Outlook controls most annual grasses and broadleaves, and it suppresses emerging yellow nutsedge. It does not control weeds that have germinated and emerged. |
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| Dual Magnum 24C label for vegetable crops Bernie Zandstra Horticulture To register to use Dual Magnum on vegetable crop and to obtain the label follow these instructions:
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| Disease management begins in the greenhouse Mary Hausbeck Plant Pathology Damping-off (caused by Pythium spp., Phytophthora spp. and Rhizoctonia sp.) affects all vegetable seedlings and is also common among flowering bedding plants. Damping-off results in collapse of the plant at the soil surface. To prevent damping-off, avoid over watering because some fungi that cause damping-off prefer wet conditions. Good sanitation is the key and ensures that root rot problems from one crop are not carried over to another crop. Root rot pathogens survive in the greenhouse in soil particles or plant parts clinging to containers, benches, walkways and equipment. If root rot occurs, remove and destroy the diseased plants. Also, remove healthy-appearing plants that are immediately adjacent to the dead plants, because the disease may have already spread to them although they are not yet showing symptoms. Plug sheets containing diseased transplants should not be reused. Table 1. Products used in trials
**Labeled for field and greenhouse use. Greenhouse fungicide trial – Rhizoctonia A greenhouse trial was conducted using registered and nonregistered products (Table 1). Inoculum was prepared by growing R. solani on potato dextrose agar for four weeks. Flasks filled with two parts millet and one part water were sterilized. Four 1.5 inch plugs of the infested agar were then placed into the flasks. The infested millet was allowed to grow for three weeks before being mixed (8 oz/1 ft3) into a soilless media (Baccto Professional Planting Mix, Michigan Peat Company, Houston TX). Three weeks after seeding into a 288-cell tray, healthy celery ‘Dutchess’ seedlings were planted into 3 inch pots containing the infested soilless media. Plants were watered as needed and fertilized twice weekly with 200 ppm of Peter’s 20-20-20 water soluble fertilizer (The Scotts Company, Marysville, OH). Eight plants per treatment were placed into a completely randomized design. Immediately after transplanting the seedling into the infested soil, fungicides were applied as a drench in sufficient volume to displace 10 percent of the water in the pots on the February 1 and 15. A plant health rating (1 to 5; 1=healthy, 2=chlorosis/minor wilting, 3=moderate wilting, 4=severe wilting, 5=plant death) and death percentage were assessed on February 7, 14 and 23. Disease pressure was severe in this trial with 100 percent of the untreated inoculated plants dead just 7 days after inoculation (Table 2). All treatments had significantly better plant health ratings and lower plant death percentage than the untreated control throughout the trial. Terraclor 75WP, Moncut 70DF, and Scholar 50WP were the only treatments that completely prevented plant death in this trial. Kocide 2000 54DF, although statistically better than the untreated, did not offer acceptable disease control. No phytotoxicity was noted on any of the treated plants in this trial. Table 2. Control of Rhizoctonia root rot of celery seedlings with fungicide drenches
**Column means with a letter in common are not significantly different (Fisher’s LSD; P=0.05). Greenhouse fungicide trial – Pythium A fungicide trial was conducted to test various products against Pythiumdamping-off in the greenhouse (Table 1). Inoculum was prepared by growing several Pythium spp. on dilute V8 agar for 2 weeks. Flasks filled with two parts millet and one part water were sterilized. Six 4 centimeter plugs of the infested agar were then placed into the flasks. The infested millet was allowed to grow for four weeks before being mixed (8 oz/1 ft3) into a sterilized soilless media. Several 288-cell flats were cut into sections of 48 cells and filled with the infested soil. Celery ‘Dutchess’ seeds were planted into each cell on 29 Sep. Six 48-cell flat sections were used per treatment and placed into a completely randomized design. Fungicides were applied as a drench. The percentage of emerging celery seedlings was noted on September 20 and October 5. Disease pressure was severe in this trial with the untreated inoculated flats averaging just 18.8 emerged seedlings compared to the untreated healthy control with 64.8 on October 5 (Table 3). On the final rating date, Aliette WDG and Banrot WP were the only treatments that had statistically more emerged seedlings than the untreated inoculated control according to our statistical tests. Due to the resistance of the Pythium spp., Subdue MAXX was statistically similar to the untreated inoculated control and did not limit disease. No phytotoxicity was observed on any of the treated plant in this trial. Table 3. Control of Pythium root rot of celery seedlings with fungicide drenches.
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| Minimize the risk of frost damage when shooting for earliness Mathieu Ngouajio Horticulture The expression “the early bird catches the worm” is well known by most vegetable growers. This is particularly important in regions like Michigan where climatic conditions restrict the growing season to a very short window for most vegetables. Because of the potential of frost damage in Michigan, most vegetable crops are usually planted within a narrow window of time. For most of the growers, the crops reach maturity at the same time and the harvest time is synchronized. Ultimately, all growers hit the market simultaneously. The peak in produce supply is normally followed by a significant drop in the price paid to growers. Growers who get in the market earlier (early birds) or later (late birds?) may take advantage of a better price. This note deals mainly with season extension strategies for earliness. Earliness usually involves planting the crop earlier than the rest of the industry. Therefore, growers who shoot for earliness take the risk of crop damage from late frost. Here are a few tips that could help minimize the risk of frost damage.
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| Application technology for small acreage producers Roberta Dow Northern District Water Quality Educator Michigan Groundwater Stewardship Program Michigan State University Extension This workshop is designed for pesticide applicators working with nurseries, greenhouses, vegetables, floral, forest and other small acreage settings. June 14 from 6:00 – 9:00 PM Northwest Horticultural Research Station 6686 Center Rd. Traverse City, MI Dr. John Grande, Snyder Research Farm, Rutgers University will be the featured speaker. Different types of liquid applicators (pump and powered backpack sprayers, backpack mist blowers, small – <150 gallon – sprayers mounted on Mule, etc.) will be demonstrated, discussed and calibrated. Modifications for different usage will be presented. Spray efficacy will be demonstrated.Attendees will gain hands-on experience. Two core recertification credits for commercial and private applicators have been applied for. The cost is $5. The rest of the program expense is sponsored by a North Region Project GREEEN grant. To register, send check for $5 to Roberta Dow, MSU Extension Grand Traverse County, 520 W. Front St., Traverse City, Michigan 49684-2208. For more information, contact Roberta Dow, dowr@msu.edu |
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Regional reports Temperatures during the week ranged from highs of 53º to 79ºF and lows from 39º to 51ºF. Soil temperatures are currently in the upper 50s. We had 2.5 plus inches of rain across the area. There was some hail on Monday, April 30, but no damage occurred on vegetables. Field activity Soil is being prepared and plastic laid. Rainfall last week created ideal conditions for laying plastic, so a lot was laid over the weekend. The soil surface is getting dry again. Crop reports Asparagus harvest volume is increasing due to higher temperatures. No problems have been reported at this time. Tomatoes, yellow squash, zucchini and cucumbers have been planted in low tunnels. Windy conditions have caused some tunnels to be blown off. Non-protected plantings will go out this week. |
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3 -- Oceana County Most areas of the county received at least 1.25 inches of rain over night on Monday, April 30 and into the morning of Tuesday, May 1. Some fields were already too wet to work from the heavy rains last fall and in March. This rain will delay field activity in those fields for a while. However, we are going into asparagus harvest with our soil moisture in excellent shape and any herbicides that were applied before the rain should be well incorporated. Crop reports A little bit of asparagus has been picked from year old plantings and from warm, sheltered fields, but no commercial quantities of asparagus will be picked until later this week. In northern Oceana County where rye cover crops were very heavy and mowing of that cover crop was delayed, harvest may not start in any quantities until next week. Labor supplies are not as tight as feared earlier, with some spot shortages and some growers with extra labor. Asparagus crown harvest was delayed by cold weather and snow in early April, so planting is delayed. That has worked out well for us since labor was late in arriving and many growers were waiting on the Cannonball Section 24C Label so that crowns could be soaked before planting. Plantings both with and without Cannonball are going on now. Adequate rains this spring should result in good weed control in asparagus. Early emerged spears exhibit a lot of white cutworm damage, but that may not be too surprising considering the warm winter we had. Insecticide applied last week seems to be taking care of the problem in later emerging spears. Processed asparagus growers are getting a slight increase this year, and initial fresh prices are also very good. The majority of carrots are planted, but wet fields remain and with recent rains may remain unplanted for a while. This rain is also interfering with application of pre-emergent Lorox. Some growers also worry about cover crops growing so quickly that they will be too big before they can get back in to spray for them. The flip side is that between good cover crops and wet soils there has been virtually no wind damage to carrot stands this year. Snap bean processors report getting adequate acres contracted to supply the plants, but many processors had to go farther a-field than normal to sign contracts. |
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4 -- Mason-Newaygo counties Weather A good start on carrot planting in the area occurred during the April 13-21 time period. Planting will continue with favorable soil conditions through May. Onion planting began also during the week of April 15. Planting will be completed as soon as soil conditions permit. |
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5 -- Macomb, St. Clair and Lapeer counties April of 2007 was full of surprises including some frigid temperatures, snow and balmy weather. Thankfully, there have been no temperature extremes since mid-April. Precipitation for the month in central Macomb was 2.6 inches. Mean soil temperatures on mineral soil hit a seasonal high of almost 60ºF on Monday, April 30. For most growers, this was not the April to get an early start, although there were warm temperatures and drying winds in mid-April that provided windows for working well-drained and muck soils and top-dressing cover crops. A lot of ground was worked this past weekend. Field work came to a halt on May 1 when an inch of rain fell. Muck soil planting progress has been steady with a fair percentage of seeding and transplanting accomplished. Greenhouses are full of vegetable transplants, some hardening off on trailers. Crop reports On organic soils, onion planting is reported to be about half completed. Carrot planting was well underway until the rain yesterday. Early lettuce has been seeded and transplanted. Growers in Macomb going for a very early crop have established leaf lettuce on plastic and bare ground for the past week or so. Early cabbage is getting established. Hothouse rhubarb is still being shipped, but the season is nearing an end. |
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Weather news Upper air ridging and high pressure will move into the Great Lakes region Wednesday, May 2, setting the stage for an extended period of fair and dry weather. Following normal to below normal temperatures during the next couple of days, look for a gradual warming trend by late in the week, with readings returning to above normal levels again by the upcoming weekend. Daytime temperatures will remain in the upper 50's to upper 60's Wednesday, gradually warming to the upper 60's to the mid or upper 70's by Saturday, May 5. High temperatures may reach the 80 degree mark in some locations by Sunday, May 6. Low temperatures will range from the 30's to the low 40's in the mornings of Thursday and Friday, warming to the 40's to low 50's by Sunday. Given a very dry air mass in place across the region, some scattered frost is possible later this week, mainly in low-lying areas on Thursday or Friday morning should clear, calm conditions materialize. Present indications are that most areas should remain well above freezing. |
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