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| Vegetable Crop Advisory Team Alert newsletter | |||||||
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| Vol. 23, No. 5, May 21, 2008 |
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| In this issue Insect update Impacts of a cool spring on cover crops and vegetable crops management Vegetable weed control during cool growing conditions Buckwheat cover cropping for vegetables 2008 MSU Weed Tour Emergency Ag Relief Act Regional reports Weather |
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| Insect update In general, few insect problems have been reported in vegetables during the past week. The recent cool weather has inhibited growth and development of many insects, but is conducive for activity and egg laying of maggot flies (onion maggots, cabbage maggots, seed corn maggots). Adults have been captured on yellow sticky traps placed in and around onion, cabbage and sweet corn fields. Maggot damage has been found in cabbage fields in southeast Michigan along with diamondback moth larvae. Very low numbers of aster leafhoppers have been captured in celery fields in southwestern Michigan. In the next week, insect activity may increase dramatically. Degree days have accumulated to a point where many insects will become active as soon as temperatures warm. Also, a change in weather patterns will bring migratory insects such as aster leafhopper and potato leafhopper into the state. Stay tuned. |
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| Impacts of a cool spring on cover crops and vegetable crops management At this time in 2006, we were all concerned about the effects of a warm spring on crop production. Then in 2007, we had a more “normal” spring in many regions. This year we have been experiencing a rather cool spring. Temperatures across the state have remained significantly below normal values and that is likely going to have important effects on the entire growing season. Impact on spring-planted cover crops Spring cover crops (mainly cool season species like mustards) are generally planted the first half of April, in preparation for June planting of vegetable crops. With the cool weather, growth of those cover crops has been extremely slow and biomass production at this moment is generally less than 50 percent of the expected values. In some cases, the cool temperatures have triggered flowering in some species like yellow mustard at a very young stage when the plant was only four to six inches tall with two to four leaves. Overall, the small biomass produced will reduce the benefits of the cover crops. Impact on bolting Bolting is a physiological disorder that results in a premature formation of the seed stack (flowering) in many vegetable crops. The problem is caused by exposure to cool temperatures like those that we have been experiencing over the last two weeks. Different varieties have different levels of bolting susceptibility. Celery and crucifers (Chinese cabbage, cabbage, broccoli, etc.) are some of the crops that growers should watch for this problem. Impact on earliness The expression “The early bird catches the worm” is well known by most vegetable growers. Earliness usually involves planting the crop earlier than the rest of the industry. However, under cool weather the efforts of the early bird might not always pay off because the seed does not germinate when the soil is cool, and seedlings stop growing under cool weather. This is probably a year when growers who invested in season extension strategies (low tunnel, row cover, plastic mulch, etc.) may benefit significantly from their investments. Impact on harvest schedule Sequential planting is a technique used by many growers (celery, sweet corn etc.) to spread harvests over a long period, therefore providing consumers with fresh, high quality, locally grown produce. Cool weather can delay germination and slow down plant growth. As a result, maturity can be concentrated at a specific time during the season despite a careful planning and staggered planting by the growers. Although it is too early to predict harvest concentrations, this is the time for growers to start developing strategies in the event that unpredicted peaks in maturity occur. |
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| Vegetable weed control during cool growing conditions The cool, dry growing conditions have complicated weed control programs in many crops. Preemergence herbicides do not work well when there has been little moisture after application. Consequently, weeds germinate and emerge when the crop is still too small for postemergence applications. In addition, small grain cover crops are tough and do not respond to graminicide applications. As soon as growing conditions improve, the weeds and cover crops will grow rapidly, but growers will have to wait to apply postemergence herbicides to avoid crop injury. Maximum weed control is important to obtain maximum yields, but stand thinning or severe crop injury from herbicides can reduce yields. As a general rule, be conservative in herbicide applications during cool weather. If irrigation is available, apply one-quarter to a half inch of water within two to three days of herbicide application to activate and incorporate herbicides into the soil moisture zone. If weeds emerge before crop plants have grown to size required on herbicide labels, it is wise to wait until the crop is larger and able to withstand the herbicides, then apply a higher rate (if labeled) of the postemergence herbicides. With small grain companion crops, it is important to kill them before they compete for moisture with the crop plants. During cool weather, increase the rate of the graminicides to improve kill of the cover crops. If the graminicides are applied alone, include crop oil concentrate (COC) or nonionic surfactant (NIS) in the mix. If other postemergence herbicides are included, it may be wise to avoid the adjuvant to reduce chances for crop injury. Most crops continue to produce roots during cool weather, and as soon as it warms up, the foliage will grow rapidly. Be ready with your choice of herbicides to spray as soon as the weather improves. When air temperature exceeds 70ºF for several days, most crops become very tolerant to labeled herbicides. If you are in doubt about a situation, please contact your county extension educator or me directly. |
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| Buckwheat cover cropping for vegetables Buckwheat can be used as a cover crop to improve soil health and fight weeds in any six to seven week window in vegetable production systems. Now (mid-May) is a good time to sow buckwheat in fields that will be planted with a late vegetable crop. Buckwheat is also a good choice following early-harvested vegetable crops like peas and before winter grains. A new Cornell University handbook (http://www.nysaes.cornell.edu/hort/faculty/bjorkman/buck/Buck.html ) provides practical information on the use of buckwheat in several cropping systems. Why plant buckwheat? Buckwheat is an ideal smother crop for weed suppression. Its rapid growth blocks sunlight and prevents weeds from establishing successfully. In idle fields with high weed pressure, two successive plantings of buckwheat can suppress annuals and weaken tough perennial weeds like quackgrass. Our recent studies have shown that incorporated residues of buckwheat can selectively suppress germination of several weed species including redroot pigweed; certain vegetables, including peas can also be inhibited, but only when planted into fresh residue. Buckwheat is also reported to extract phosphorous and improve soil aggregation through secretions from its fine roots, mellowing the soil for establishment of subsequent crops. In addition, many beneficial insects are attracted to buckwheat. Among the 19 plant species examined by MSU entomologists, buckwheat ranked fifth in the number of beneficial insects attracted (http://nativeplants.msu.edu/fagesc.htm). Limitations Buckwheat is sensitive to frost, so it cannot be planted as early or as late as alternatives like oats or mustards. Buckwheat is also sensitive to several herbicides including atrazine, Pursuit, Sandea and Reflex and therefore cannot be successfully planted following crops using those herbicides. Some growers report problems with volunteer buckwheat in subsequent crops if mowing and incorporation is delayed. Management tips Drill at 50 lbs/acre at one inch or less for most effective establishment. If broadcasting, use 70 lbs/acre and shallow incorporate. To reduce risk of buckwheat seed production, mowing and incorporation should occur within 10 days of flowering (about 40 days after sowing). Buckwheat does well on a wide range of soil types and can perform well on infertile soil, but does not tolerate excessively dry or wet conditions very well. For more information about buckwheat and other cover crops, attend the upcoming workshop “Cover Cropping in Vegetable Systems-An Essential Tool for Sustainable and Organic Farmers” on June 12 from 9:00 AM to 5:00 PM at the Kellogg Biological Station. For registration and the agenda, please go to http://www.michiganorganic.msu.edu/ or call the MSUE Oceana County office at 231-873-2129 or email Kathy Walicki: walicki@msu.edu. |
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| 2008 MSU Weed Tour We invite you to make plans to attend the annual Michigan State University Weed Tour, on Wednesday, July 2 beginning at the MSU Botany Field Lab (located on College Road, north of Jolly Road). Registration begins at 9:00 AM with the field tour kicking off at 9:30 AM. The tour will provide ample opportunity to look at research plots and participate in some short field presentations. (Be sure to bring a hat and sun screen.) Participants can compare their favorite corn and soybean herbicide programs to other commercial programs and evaluate how new transgenic crops interact with weed management strategies. The morning tour ends with lunch. The afternoon tour will begin at 1:00 PM at the MSU Horticulture Farm (College Road, south of Jolly Road) and will include weed control research in horticultural crops. Pre-registration for the tour is $25 per person which includes a tour booklet and a lunch ticket. A flier with a map and registration form is enclosed in this issue and is also available online at www.msuweeds.com, or can be obtained by contacting Deb Misiak at 517-355-0271 ext. 1112, email: misiak@msu.edu. |
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| Emergency Ag Relief Act The Senate Appropriations Committee approved legislation sponsored by Senators Feinstein (D-Calif.) and Larry Craig (R-Idaho) that would provide relief to the agricultural employers and farmworkers on May 15. The legislation was attached to the Iraq supplemental spending bill. Different from the stalled AgJOBS legistlation EARA, this is emergency legislation with a five year sunset and does not provide a path to citizenship or a green card. However, it would grant temporary immigration status to farm wokers who continue to work in agriculture at least 100 days per year. It would also modify the H-2A guest worker program. The bill is supported by many agricultural employer organizations (e.g., American Farm Bureau), agricultural labor advocates and farmworker organizations (e.g., United Farm Workers). More information is available at http://feinstein.senate.gov/public/index.cfm?FuseAction=NewsRoom.PressReleases&ContentRecord_id=ee2d9ac8-ebdb-0a1c-48c1-484dfc65e9d9 If you or your clientele would like to support or oppose this legislation, it is paramount to act quickly. |
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| Regional reports 1 -- Southwest Ron Goldy Weather Temperatures for the period were below normal by 5 to 15 degrees. Lows ranged from 34oF to 50oF and highs from 53oF to 67oF. Some frost occurred on May 19. Soil temperatures are around 50oF. There was 0.2 inches of rain for the period. Weather remains conducive for field work, but not for significant plant growth. Field activity is keeping pace with previous years, but we are around 15 days behind in plant growth. Crop reports Asparagus harvest continues at a slow pace without any unusual problems. The pace should increase significantly with the increase in temperatures predicted for the weekend. Tomato planting continues. Suckering of tunnel-grown plants has begun. Tunnel-grown vine crops have progressed little over the past week.Germination and growth of direct seeded crops is slow due to cold soil and air temperatures. |
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| 2 -- Grand Rapids Area Bill Steenwyk Weather The cool temperatures we're all experiencing are most evident when driving around the countryside, noticing that the thousands of acres usually green with growing corn and soybeans are still displaying only bare ground. All but the most cool weather plants are developing at a snail's pace. The warmer weather anticipated later this week will be very welcome. Crop report Regarding muck crops, celery transplanting continues at its normal, seasonal pace. A few aster leafhoppers were found in one field. Despite the delayed growth, there are no major problems. The same holds for beet, radish and leek plantings. Onion development rages from newly emerged to the two-leaf stage. As the barley cover crops were killed, a few farmers noticed some areas hurt by the freezing temperatures of April 30. A few acres were replanted. Yellow nutsedge is beginning to show itself on some muck fields. On upland areas, the largest sweet corn I've seen is the two-true-leaf stage (where the leaf collar is visible). Cabbage transplanting continues, and fields look good. Some of the warm-season crops are in the ground, but overall planting and transplanting progress has been delayed. | ||||
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| 3 -- Oceana County Norm Myers Weather Weather has continued to be cool and dry. We had some frost on Monday, May 19 in the morning with temperatures at Lakeshore and in Crystal Valley reported as low as 29ºF, but the automated weather station at the Asparagus Research Farm only got down to 33ºF. Soil temperatures have remained down in the 40s most mornings over the last week which has limited germination of annual crops. Crop report Spotty, light frost damage was experienced in many parts of the major growing areas for asparagus. There was more damage to year-old and early 2008 plantings where the spears were taller and further from the heat radiated from the soil, but most growers seem to feel that the plants would recover. Most growers have switched over to cuts and tips production partly because of frost damage and partly because the fresh market has cooled off. Cool temperatures have resulted in almost no asparagus beetle problems so far this year. Carrots are emerged in most fields, but it should not have been cold enough to hurt any plants. Growers are beginning to kill off cover crops in early planted fields and a little post emergence weed control has begun. In sweet corn, cold soil temperatures have delayed emergence, even though there is still enough soil moisture to germinate seeds. For vine crops, processors would like growers to begin planting on May 22, but growers are understandably hesitant to plant in to such cold soil conditions. |
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| 4 -- Mason-Newaygo counties Jim Breinling Weather The past seven days have been a repeat of the previous week regarding temperatures and rainfall. The low temperature reported the past week at the Fremont Enviro-weather station was 30.8ºF on the morning of May 19. Three low temperature readings this past week at the Ludington weather station were at or below freezing with 30.2 ºF, 31.6 ºF and 32 ºF recorded. Rainfall continues below normal with 0.2 inch recorded at Fremont compared to 0.46 recorded at the Ludington station in Mason County. Soil conditions especially in Mason County have been good for planting this past week. Crop report The extended cool weather has even seemed to have slowed the growth of peas. Plantings are at the 7th and 8th node growth stage with first bud formation. Early carrot plantings are at the first true leaf stage. Rows are readily visible now within the protective cover crops, and overall stands appear to be good. Onion plantings are generally in the flag stage. Herbicide burndown of cover crops is underway. Early plantings of parsnips are at the first true leaf stage. Spinach also is at the first leaf. Potatoes were emerged on May 15 and appeared to have escaped any damage from low temperatures early that morning. |
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| 5 -- Macomb, St. Clair and Lapeer counties Hannah Stevens Weather The weather continues to be sunny, breezy and cool throughout the region with scattered frost on Monday, May 19. This was no surprise and hopefully there was little crop injury. Minimum soil temperatures have been in the 40-50ºF range. There has been no precipitation this week. Field activities are well under way with many acres of plastic mulch, row covers, trellises being set and warm season crops being planted. Barley cover crops are being killed this week on the organic soils. Crop report Spring picking of over-wintered spinach is nearly over. Seeded fields and transplanted onions are doing well. While onion maggot adults are plentiful on our sticky traps, there has been no injury noted. Flea beetles are damaging young cabbage transplants that are recovering from frost and growing slowly in these cool temperatures. In sweet corn, there has been little change since last week. Young plants are yellow and emerging slowly. For snap beans, one early field I am following is in the seed leaf stage and emergence looks good. |
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| 6 -- Monroe County Sudeep Mathew Weather It has continued to remain cool this last week throughout the region. Soil temperatures were in the 47-60°F range during the past week. Growers have delayed transplanting cucurbits, peppers and melons until this weekend’s anticipated warmer temperatures. Crop report Processing tomato growers are nearly 50 percent planted. Early planted fields looked good. Vine crops that have been transplanted or seeded have made very little growth. Colorado potato beetle were found feeding on nightshade in a cucumber field. No cucumber beetles have been found yet. Cabbage fields have excellent stands and early planted fields have made great growth. Growers that treated at planting time have very little maggot damage. Diamondback moth larvae were found in several fields this week (Photo1). In one cabbage field, symptoms were found that resemble Molybdenum deficiency (Photo 2). | ||||
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Weather news In the short term, more clouds are likely statewide Wednesday, May 21st and Thursday, May 22nd, with a chance for showers. However, given only very limited low-level moisture in place ahead of the system, any rainfall should remain very light (less than 0.1 inch) and scattered at best. Drier and gradually less cloudy conditions are expected by late Thursday and Friday. Temperatures Wednesday and Thursday will remain at much below normal levels from the mid and upper 40=s far north to mid- or upper 50=s south to lows in the low or mid- 30=s north to near 40ºF south. As noted in last week=s column, while the next couple of nights are expected to be cloudy and relatively windy, frost is a possibility Thursday and Friday mornings should clear, calm conditions develop. Greatest chances for any frost would be in inland, northern sections of the state. Further ahead, a significant warming trend is expected to begin by Friday as the upper air ridge approaches from the west. Temperatures by Saturday and Sunday should climb back in the upper 60=s north to the mid- to upper 70=s south by Sunday with lows in the 40=s to low 50=s. It is possible that high temperatures may approach 80ºF in some sections of the state Sunday and on Memorial Day (next Monday). In terms of precipitation, dry weather is expected for most of the upcoming weekend, with a chance for showers and thunderstorms on Monday as a frontal system approaches from the west. In the medium-range forecast period, the upper air ridge mentioned above is expected to give way to a flatter, more west to east flow pattern for the 6-14 day period with an active weather pattern across the Upper Midwest. The National Weather Service 6-10 day out look covering May 26 to May 30 calls for near normal mean temperatures and for precipitation totals ranging from near normal in eastern sections of the state to above normal in the west. The 8-14 day outlook for May 28 through June 3 calls for near normal temperatures and above normal precipitation totals statewide. |
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