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Vegetable Crop Advisory Team Alert newsletter

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Vol. 23, No. 6, May 28, 2008

In this issue

Herbicide sensitivity in potatoes

Onion weed control during cold growing conditions

Dual Magnum registered for pumpkins

Agricultural labor statistics for spring 2008

Pesticide residue testing

Regional reports

Weather

Herbicide sensitivity in potatoes
Wesley Everman
Crop and Soil Sciences

Potatoes have a wide variation in growth habit and response to environment, particularly due to genetic variation which can be attributed to its polyploidy nature. It is therefore no surprise to those who grow potatoes that varieties respond differently to herbicide applications. Herbicide options for weed control in potatoes are limited to several compounds that have been around for decades with a few newer ones mixed in. Herbicide injury in potato varieties with Sencor is well documented and is taken into consideration when planning Sencor use for weed control. The cool weather this spring has created conditions that favor the enhancement of herbicide injury in crops. Cool weather slows the metabolism of herbicides in the crop, which allows the herbicides to block pathways and induce injury not normally observed in potatoes. Coupled with the inherent sensitivity of some varieties, severe injury can occur.

Potato varieties, such as Atlantic or the newer Silverton Russet, grown in Michigan that show varietal sensitivity to herbicides on a normal year, may show greater injury when the weather has slowed potato growth. Potatoes are commonly sensitive to Sencor/Lexone (metribuzin), however, herbicides that potatoes are not generally sensitive to, including Dual Magnum /Cinch/Parallel/Stalwart (metolachlor), Outlook (dimethenamid-p), Lorox (linuron) and Matrix (rimsulfuron) can cause injury under adverse conditions, such as cool, wet weather, when soil applied. Injury can also be observed after herbicide application in hot, humid weather. It is important to time herbicide applications to avoid coinciding with stress-inducing conditions to help avoid injury. Some herbicides such as EPTC can cause wrinkled leaves and other injury if applied at a rate exceeding label recommendations. Drift is also a concern during the growing season with glyphosate and phenoxy herbicides, such as 2 4-D, causing injury to emerged plants.

This spring injury due to the cool weather has been observed after Sencor and Lorox applications. Injury symptoms for Sencor (Figure 1) include interveinal whitening and yellowing of the leaf, generally most evident on the older leaves. Similar injury symptoms occur with Lorox (Figure 2), however whitening and chlorosis often occurs on the leaf margin. Many nutrient deficiencies and environmental stress responses can resemble herbicide injury, therefore if you suspect you have herbicide injury, contact your local Extension educator to help diagnose symptoms accurately.

Herbicide rates and recommendations for weed control in potatoes can be found on pages 118 to 123 with weed and crop response ratings on page 125 in 2008 Weed Control Guide for Field Crops


Figure 1. Sencor injury on potato. Credit: W. Everman	Figure 2. Lorox injury on potato. Credit: W. Everman

Onion weed control during cold growing conditions
Bernard Zandstra
Horticulture

The prolonged cool growing conditions this spring have complicated onion weed control plans. Most seeded onions are growing very slowly with some just emerging, and others in the 2 leaf stage, often in the same field. Weeds are germinating, and small grain cover crops continue to grow. Growers face a dilemma regarding what to do next.

An old physician (Greek?) adage is “Do no harm.” That is good advice for onion weed control under these conditions as well. Whatever we do, we don’t want to thin the onion stand too much or inflict permanent injury that will result in yield loss. A good rain and a couple of warm days will encourage most of the onions to reach the 2 leaf stage soon. A few lagging seedlings won’t be missed.

Once the onions are growing well, the remaining small grain (primarily barley) cover crops should be killed immediately with a high dose of one of the grass killers. Two to three days after a killing application, you should be able to pull the youngest growth out of the heart of the barley plant. There will be brown discoloration at the point that it breaks. If a number of growing points do not pull out easily and do not demonstrate the brown color, you have not killed the cover crop and you will have to spray it again. Use the highest recommended dose of any of the registered graminicides for onions.

If broadleaf weeds have germinated and are growing rapidly, the onions should be sprayed with GoalTender as soon as possible after the onion 2 leaf stage. Use 2-4 fl oz of GoalTender if weeds are larger than 0.5 inch tall and have true leaves. Once the onions have reached the full 2 leaf stage and the third leaf is coming, they can be sprayed with Chateau at 2 oz per acre. It will extend preemergence control for most weeds, and also burn off most weeds surviving the GoalTender applications. Do not tank mix Chateau with any other chemicals.

If yellow nutsedge is a problem, apply Outlook or Dual Magnum as soon as the onions reach the 2 leaf stage. Application earlier than that can result in stand reduction, especially in cool weather. These herbicides have no effect on emerged nutsdege, and need to be watered in to be effective.

If you have specific questions about your onion weed control program, please call me for advice. (517-353-6637).

Dual Magnum registered for pumpkins
Bernard Zandstra
Horticulture

The United States EPA has approved a label for use of Dual Magnum on pumpkins. It is a supplemental label, which is part of the regular Section 3 label. This means that it is not an indemnified label needing special record keeping.

The label allows application of Dual Magnum at 1.0-1.33 pt per acre before the crop and weeds emerge. It should be applied to the areas between the rows and not directly over the crop row. This is to avoid crop injury as the plants emerge. The label mentions broadcast applications and explains the risk for use in that manner, but does not completely exclude it. In my experience, there is very little risk for use of Dual Magnum as a broadcast spray after seeding pumpkins, and also winter squash, which are not on this label. We may be able to obtain a Section 24c (SLN) state label for winter squash in the future.

Copies of the label should be available from dealers, on the Syngenta website, or from the MSU vegetable website: www.veginfo.msu.edu.

Agricultural labor statistics for spring 2008
Vera Bitsch
Agriculture, Food and Resource Economics

This April, the hourly wage for agricultural workers in the United States stood at $10.60, up 40 cents from a year ago. Field workers received $9.65, up 30 cents from a year ago. Livestock workers made $10.32, up 63 cents from a year ago. This wage rate includes supervisors and other workers, such as bookkeepers and pilots. Wage rates do not include the value of benefits. Total hired workers are estimated at 919,000 individuals, down by 7 percent compared to last year. The number of hours worked is up only slightly at 41 precent

Michigan, Minnesota and Wisconsin make up the Lake region. For the three states, the number of hours worked stood at 39.0 hours during this April. The total number of workers, excluding agricultural service workers, is estimated at 52,000 individuals, compared to 56,000 during last April. The average wage rate for all hired workers was $11.25 per hour, up 17 cents from a year ago. Only, Hawaii with $13.28, the Cornbelt I region (Illinois, Indiana, and Ohio) with $11.43, and the Cornbelt II region (Iowa, Missouri) region with $11.88 paid higher wages. Field workers in the Lake region earned $10.57 per hour, up 46 cents. Livestock workers earned $10.78 per hour, up 79 cents.

In addition to analyzing wage rates by type of worker, NASS provides wage data by type of farm with slightly different results. These data combine field workers and livestock workers, but exclude other typically higher paid groups. The average hourly wage rates in 48 states, excluding Alaska and Hawaii, during this April were $9.87 overall, $9.84 for field crop farms, $9.66 for other crop farms, and $10.20 for livestock and poultry farms. Last year those rates were $9.41, $9.36, $9.39, and $9.47, respectively, indicating notable wage increases.

The hourly wage rates in the Lake region were $10.70 for all farms, $10.08 for other crops, and $10.78 for livestock and poultry farms. There was insufficient data to calculate the wages for field crop farms. Last year the wages in the Lake region were $10.05 for all farms, $10.82 for field crop farms, $9.72 for other crop farms, and $10.13 for livestock and poultry farms. Overall, the Lake region has seen considerable wage increases.

To read Dr. Bitsch’s complete newsletter go to her website at http://www.msu.edu/user/bitsch. Under “News” click on “U.S. Agricultural Labor Statistics for Spring 2008” or click on “Agricultural Labor Issues in Michigan” for a list of available newsletters.

For more details, the NASS release is available at http://www.usda.gov/nass/. Select “Publications” and then “Reports Calendar” or “Publications” and then “Search,” by “Title” or “Subject” (Farm Labor).

Pesticide residue testing
Steven Gower
MSU Diagnostic Services

Herbicides can injure desirable, non-target plants in a variety of ways, including drift, volatilization, carryover, tank contamination, misapplication or simply accidental or intentional exposure. In addition to diagnosing plant pathogens, nematodes and insect-related pests, all plant samples submitted to MSU Diagnostic Services – the multi-disciplinary plant health and pest diagnostic facility on campus – are visually inspected for pesticide injury. If warranted, samples can be tested for the presence of pesticide residue using appropriate analytical instruments and techniques.

Sampling
We urge clients that are interested in pesticide residue testing to contact the laboratory before collecting and submitting samples. Samples should be collected immediately if pesticide injury is suspected. If you suspect a drift event has occurred but are not positive, it may be wise to collect a tissue sample that day or the next and place the sample in the freezer. Glyphosate and 2,4-D, for example, can be very difficult to detect and quantify in the tissue once injury symptoms develop. Therefore, a little foresight in sampling may really help if injury symptoms do develop 7 to 10 days later. Collect enough plant tissue to fill a quart-size plastic bag; collect enough soil to fill a pint-size plastic bag. In general, samples should be frozen immediately and kept frozen until arrival at the laboratory.

Fees
Plant samples are visually inspected for pesticide injury for $20. Samples can be tested for pesticide residue on an individual basis or, if available, in multi-pesticide screens. Fees may vary depending upon number of samples, clientele location and numerous other special circumstances. Fees for individual pesticide residue screens are generally $90, $100 and $125 in water, tissue and soil, respectively. Fees for multi-pesticide residue screens are generally $125, $150 and $175 in water, tissue and soil, respectively. Questions regarding pesticide injury or pesticide residue testing should be directed to Steven Gower by phone at 517-432-9693 or email at sgower@msu.edu.

Regional reports
1 -- Southwest
Ron Goldy

Weather
Lows for the area ranged from 41oF to 59oF and highs from 53oF to 79oF. Soil temperatures are in the low to mid-60s. There was 0.18 inches of rain for the period. We have only had about 0.4 inches of rain over the past two weeks, so irrigation is being applied to drought prone sites. Warmer temperatures over the weekend contributed to increased plant growth, but the biggest difference is in the uptake of nitrogen contributing to a greener appearance of the plants.

Crop report
A slow asparagus harvest continues. Growers are on about their fifteenth harvest.

Direct seeding of vine crops and transplanting of tomatoes continues.

Pepper transplanting will start in a big way over the next few days.

Early planted sweet corn is about six inches tall.

Colorado potato beetles are active.

2 -- Grand Rapids Area
Bill Steenwyk

Weather
There is not much new to report this week, other than that the cool weather continues to retard crop growth and development. This morning, several growers reported frost in muck areas of southern Kent and Ottawa counties. It appeared to be light, but they had not yet had the chance to determine the degree of crop damage.

Crop report
Field work in planting/transplanting new fields of muck and upland vegetable crops continues.

Many onion fields are at the flag leaf to three leaf stage.

Sweet corn ranges from spike to the three leaf stage.

Cool season crops such as cabbage and peas look good.

Many acres of tomatoes, peppers and vine crops have yet to be established. Some are concerned that lack of rainfall will limit the effectiveness of recently sprayed, pre-emergence herbicides. If we can receive more heat and rain, development will progress rapidly.

3 -- Oceana County
Norm Myers

Weather
The Enviro-weather station north of Hart had 27.5 degrees this morning, but I talked to a grower this morning in the main vegetable growing area and he had 30 degrees, which is the same as I had at my house. He and I both noticed that even at that temperature, no frost formed. We have been very dry over the last two weeks and soil moisture is running out pretty quickly.

Crop report
Many growers picked asparagus fields down yesterday. I had a chance to talk to one grower this morning and it sounds like many of the harvested fields escaped damage, but we are not yet sure about the 2007 and 2008 plantings that were going to fern. We probably will not know if those were damaged until this afternoon. Yields are already dropping a little due to the dry weather. Spear diameter is suffering somewhat. On the pest front, every time the temperature spikes up, we get a spike in common asparagus beetle activity.

Early planted carrots are in the two-three leaf stage and barley/oat cover crops have been sprayed, but are dying very slowly. It should not have gotten cold enough to have hurt them in Oceana County.

Growers will begin planting zucchini next week. There are supposed to be a couple of early cucumber fields in the ground, but we certainly have nothing through the ground yet.

Some sweet corn has emerged, but growth is slow and anemic.

4 -- Mason-Newaygo counties
Jim Breinling

Weather
Temperatures continued generally below normal for the past week with a short warm period on Monday, May 26. It is too early to assess extent of frost or freeze damage that might have occurred this morning (May 28). The low temperature reported at the Fremont Enviro-weather station was 30.6ºF. Mason County appears to have been the cold spot with 26.0 ºF recorded for the low at the Ludington Enviro-weather station. Essentially no rainfall received during the past seven days in the area. There has been only 0.22 inch of rainfall recorded at the Fremont station in the past three weeks. Irrigation systems have been operating this past week in Newaygo County.

Crop report
Onions in early planted fields are now at the third leaf stage. Growers are in the process of assessing stands, but the feeling is that generally the stands will be okay.

The spinach plantings are off to an excellent start.

Carrots are now at the second to third true-leaf stage, and stands are good.

There are reports of freeze damage and plant loss in early plantings of turnips. Some flea beetle activity reported this past week.

Planting of vine crops has begun in Newaygo County. Depending on emergence, these plantings have to be assessed regarding frost
damage and stands.

The acres of snap beans to be planted in Mason County this year will be less than normal. European corn borer traps were put up yesterday in Mason County adjacent to a field scheduled for planting about mid-June.

5 -- Macomb, St. Clair and Lapeer counties
Hannah Stevens

Weather and crop conditions
This week continued to be very dry with a total of about 1.6 inches of rain measured in mid-Macomb this month. Until the Memorial Day (May 26) high temperature of 85ºF, the maximum temperatures ranged from 57ºF to73 ºF with several days of gusty winds. Growers were as prepared as possible for this morning’s scattered frost with most melons, tomatoes and other sensitive crops protected under plastic row covers or temporary covers. There may have been injury on seeded crops and muck soils where minimum temperatures were much lower. Spring seeded cover crops on the muck have been sprayed, but are responding slowly to the graminicide. Cultivation may be needed shortly. Many small weed seedlings are emerging on both muck and mineral soils.

Crop report Over-wintered spinach is holding well under the cool conditions Onion maggot adults continue to be found in traps, but no injury on the crop has been found. The crop stands and progress are good. The early cabbage crop has recovered very well from the frost of April 30. No maggot damage has been found in scouted fields. Early bare soil sweet corn is in the 5 leaf stage. There were no European corn borers or corn earworms in the traps this week. In muskmelons and watermelons, many acres on plastic and under row covers are becoming established. Drip irrigation will be needed any time now. Tomatoes that have been staked and, thus not covered, may have been injured by frost this morning.

6 -- Monroe County
Sudeep Mathew

Weather
It has been mild with some cool weather during the week. Soil temperatures were 35-73ºF range during the past week with the dry weather continuing. There was some frost the morning of May 28 with temperatures as low as 33ºF. But it didn’t seem to make much impact. A fair amount of transplanting cucumbers and peppers has been completed.

Crop report
Processing tomatoes on plastics are close to being done. Early planted fields looked good, but dry.

Vine crops that have been transplanted or seeded have been slow in growth. Colorado potato beetle was found feeding on nightshade in a cucumber field.

There was some consistent browning found at pepper fields. This was not recognized as a disease problem, and Paul Marks suspects
it may be the result of the cold nights since transplanting. Those in the field for more than one week are beginning to show new growth.

Cabbage fields that have made good growth last week are showing diamondback moth larvae activity.

Weather news
Jeff Andresen
Agricultural Meteorology
Geography

A strong area of high pressure across the Great Lakes region on the morning of Wednesday, May 28, will lead to at least one more fair and dry day in Michigan. Given cold temperatures aloft, low dew point temperatures, mostly clear skies, and calm winds, scattered light frost will be a possible once again overnight Wednesday into Thursday morning, although temperatures should remain several degrees warmer than those experienced the day before. Fair weather is expected again Thursday with an increase in clouds and temperatures as an area of low pressure approaches from the west. Showers and thunderstorms are a good bet overnight Thursday and Friday as the low moves through the state. Scattered showers will be possible early Saturday, followed by clearing late in the day.

At this point, significant rainfall is expected, especially across central and southern sections of the state (latest model-generated precipitation forecasts suggest totals in the 0.50-1.0 inch range through Saturday evening across much of this area). Temperatures during the next few days will gradually warm from highs in the 60's Wednesday to the upper 60's north to mid-70's south Thursday through Saturday. Lows will increase from the 30's to low 40's Thursday morning to the low or mid-50's by Saturday. Following the passage of the low pressure area Saturday, fair weather with seasonable temperatures is expected in most areas of the state Sunday. A second area of low pressure is expected to bring another chance for rainfall late Monday or Tuesday of next week.

In the medium‑range forecast period, a broad upper air ridge across central sections of the United States with troughs on both west and east coasts is expected to gradually transition to a more zonal, west to east flow pattern. The National Weather Service 6‑10 day outlook covering June 2 through June 6 calls for an active weather pattern with below normal temperatures and above normal precipitation totals across Michigan and the Great Lakes region. Similarly, the 8‑14 day outlook for June 4 through June 10 calls for near normal temperatures and above normal precipitation totals.

New NOAA long lead outlooks
In our discussion of the new long lead outlooks, it is worth taking note of the recent series of tornadoes and severe weather across the Midwest and other sections of the country. As of the May 23, NOAA=s Storm Prediction Center had tallied 930 tornadoes across the United States so far this year, which is more than 400 more than normal for the date and, given at least 50 more tornadoes during the past holiday weekend, approaching the normal annual total of 1,270. One of the tornadoes this past weekend in Iowa was an extremely violent Enhanced Fujita scale level 5 tornado (the most severe type) with winds in excess of 200 mph and a path more than 1 mile wide. If this unusual frequency and pace of accumulation were to continue throughout the entire 2008 severe weather season into the fall (very unlikely), this year=s total would easily shatter the all time record of 1,424 tornadoes set in 1998. Causes of the unusually active season are not completely clear at this point.

One important issue was the abnormally early start of the severe weather season in January across sections of the south. Another is the presence of a La Niña event in the equatorial Pacific, which in turn was linked with an abnormally active jet stream storm track from the southwestern United States into the Midwest (and to record heavy seasonal snowfall totals in portions of the Upper Midwest). Tornado outbreaks in the central United States are typically linked with an upper air trough in the western United States and a ridge across the east, a strong southwesterly jet stream, and to a warm and humid air mass (Gulf of Mexico origin) on the surface. These key ingredients have unfortunately been present together much more frequently than usual so far this year.

There is some suggestion in the long lead outlooks that the pattern so conducive to severe weather may gradually come to an end at some point during the next several weeks. La Niña conditions in the Pacific are expected to gradually diminish by mid or late summer, which is reflected in the new NOAA outlooks. For June, the outlook is linked to recent weather patterns and to medium-range forecast guidance in suggesting cooler and wetter than normal weather for nearly all of Michigan and other adjacent sections of the Great Lakes region. For the 3-month June through August period, the outlook for mean temperatures and precipitation totals remains in the climatology scenario of near equal odds of below-, near-, and above normal levels. The outlook generally calls for Michigan to remain between areas of cooler and wetter than normal weather across southern sections of the country and warmer and drier than normal to our west (see http://ipm.msu.edu/cat08fruit/pdf/5-27weather.pdf).

The MSU IPM Program maintains this site as an access point to pest management information at MSU. The IPM Program is administered within the Department of Entomology, fueled by research from the Michigan Agricultural Experiment Station, delivered to citizens through MSU Extension, and proud to be a part of Project GREEEN.
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