Vol. 19, No. 2, June 10, 2004

In this Issue
Armyworms among us
Availability of N to corn
New nutrient recommendations now available
Consider cultivation of corn
Nutrient Management Course offered June 22-23
2004 MSU Weed Tour brochure (pdf)
Regional reports
Weather news

Next issue -- June 17th

Armyworms among us

Christina DiFonzo, Entomology

Over the last few weeks, I've written about the likelihood of armyworms moving up into Michigan, and the potential for problems, especially given the link between infestation and poor weed control/cover crops. As soils dried and people were able to get into the field, armyworm problems are indeed becoming apparent in both wheat and corn. Larval size ranges from 0.5 to 0.75-inch, although I have had one report from Washtenaw County of 2-inch caterpillars. This article contains the scouting recommendations and thresholds for several crops.

Corn
Larvae are usually active at night or on cloudy days. During the day, they often hide in the whorl or at the base of plants. Large frass (excrement) pellets in the whorl are a sign that larvae are present. Damage is obvious as feeding on the leaf margins; in severe cases, all leaf material is eaten leaving the midrib. Treat if there are two or more larvae on 25 percent of the plants, or 1 larvae per plant in 75 percent of the stand.

Wheat
Larvae are usually active at night or on cloudy days. During the day, larvae are usually at the base of plants under residue, so you have to get down into the canopy to find them. Damage is apparent as feeding along the leaf margins. Before heading, treat at four or more larvae per square foot. After heading - to prevent head clipping - treat if there are two or more larvae per square foot.

General comments
Spot spraying may be possible along field edges or in areas that had heavy weed growth. Most larvae are only 0.5- to 0.75-inch long, and have a ways to go before they stop feeding, so spraying is justified. Pyrethroids have been particularly effective at killing small larvae. For organic wheat, there are several Bt options for treatment. See Bulletin E-1582 (available at your local Extension office or free on the web at http://www.canr.msu.edu/fldcrp/e1582.htm) for specific products and rates. If larvae are over 1.5 inches (as was the case in Washtenaw County), then caterpillars will pupate shortly and a spray is not economically justified.

Availability of N to corn

Carrie Laboski
Crop & Soil Sciences

In the May 27 issue of the CAT Alert, Darryl Warncke and I wrote an article titled Nitrogen Losses Due to Excessive Rainfall. In that article, we suggested that the best way to know how much fertilizer N may still be in the soil is to take soil samples at the 0- to 1-foot and 1- to 2-foot depths and have them analyzed for nitrate. Table 1 shows how much N has been found in soil sampled like this. The N credit column to the far right labeled PSNT is the standard PSNT credit that would be given if only a 0- to 1-foot sample were used. The other N credit columns, proved the actual amount of N (from nitrate) that was found in that particular soil depth. For more details on PSNT credits see the May 27 article.

Table 1.

In Tuscola County, 57 and 63 lb N/a were found in the top 2-foot of soil in sandy and loamy areas of a field, respectively. This means that 23 to 29 lb N/a of applied N are not accounted for in this 2-foot sample. The nitrogen likely was lost to denitrification in the loamy soil, and perhaps leached to a deeper soil depth in the sandy soil. There was almost three times more N in the 1- to 2-foot sample than in the 0- to 1-foot sample in the sandy soil, showing that leaching did occur in parts of the field. If a standard 0- to 1-foot sample had been taken for PSNT, the N credit would have only been 25 lb/a on the sandy soil, when in fact 57 lb/a are available. In general, standard PSNT samples this season, are more likely to underestimate the amount of N in the soil; thus recommending more sidedress N than needed.

In Barry County, there was some variability in the amount of N remaining in the soil, even though the soil texture was similar for both samples. This is likely a result of frequent dairy slurry applications to this field. Generally, there is more N in the soil profile than what was applied at planting, also a result of manure applications.

If the growers in Tuscola and Barry were planning to sidedress N, they might apply 100 lb N/a or less, depending on their yield goal.

In Saginaw County, soil samples were only taken from the top foot of soil. Less actual N was found in the top foot compared to what was applied. But, there may have been some leaching of N into the second foot of soil that was not measured. Our standard PSNT test assumes that the amount of N in the second foot is two-thirds of what is in the top foot. However, the data from Tuscola and Barry Counties show that the amount of N in the second foot of soil is more than two-thirds the top foot this season. Thus, there is adequate N in this field for corn production and no other N should be applied.

Just for curiosity's sake, I have asked the Soil and Plant Nutrient Laboratory (SPNL) provide me the results of their nitrate analyses since May 20. The data listed in Table 2 shows the range in N credits as determined by the standard PSNT and the median N credit when separated by county and manure history. Note: the median value is the value where half of the samples would have a greater N credit and half would have a smaller N credit.

The samples submitted to SPNL are not labeled such that we know how much N was applied prior to sampling. Because of this, the range in N credits for non-manured fields is about as large a manured fields. Likely many growers are sampling to determine how much fertilizer N may have been lost.

New nutrient recommendations now available

Carrie Laboski
Crop & Soil Sciences

Nutrient Recommendations for Field Crops in Michigan, Bulletin E2904 was released the last week of May. This bulletin replaces Fertilizer Recommendations for Field Crops in Michigan, Bulletin E-550A. E2904 contains updated fertilizer recommendations for corn (grain, silage, & seed), dry edible beans, small grains, sugar beets, forage crops, potatoes, and grassed waterways including CRP. There is no longer a difference in fertilizer recommendations between MSU and the Tri-State bulletins. MSU recommendations for the four Tri-State crops (corn, soybean, wheat, and alfalfa), in addition to all other crops, have been changed to fully use the Tri-State approach of build-up, maintenance, and drawdown.

E2904 is available from County Extension offices or directly from the MSU Bulletin office (http://web2.msue.msu.edu/bulletins/). It is also available in pdf format at: http://web2.msue.msu.edu/bulletins/Bulletin/PDF/E2904.pdf

Consider cultivation of corn

Ned Birkey
Monroe EANRA

For later planted and shorter corn that appears to have suffered more from the May rains, consider row crop cultivation to help aerate the soil to promote good root growth. Fields that suffered ponding or heavy rains may have compacted soils that is hindering corn root growth.

Some of the shorter, later planted corn in hard, rain-packed soils may be struggling and even may appear to be "going backwards." This corn may well be yellow and not have good root growth. For farmers who have a rigid shank cultivator and who have time to perform this task, this operation will lessen soil compaction and provide oxygen to aid in good corn root growth.

Ideal soil structure includes 25 percent air, 25 percent water, 45 percent minerals and 5 percent organic matter. Near-record rains in May have beat some soils into a compacted state that is now restricting proper root growth. Depending upon the equipment, nitrogen sidedressing equipment may provide some help in this situation.

Nutrient Management Course offered June 22-23

Michigan State University Extension and NRCS will be hosting a two-day, nutrient management training class for interested farm consultants. The class will be held Tuesday and Wednesday, June 22 and 23 from 8:15 AM to 4:30 PM. Please excuse the poor timing for crops related persons, but the course is meeting a deadline requirement for Comprehensive Nutrient Management Plan (CNMP) providers. Another similar class will not be held until 2005.

If you are a CCA, this class is not required for CNMP certification, but the information will be invaluable to those who work with livestock producers. The class will cover soils, fertilizer and manures as they relate to nutrient management. A special emphasis will be placed on hands-on involvement in developing a nutrient management plan for producers that includes both manures and fertilizers for best agronomic yields and environmental protection.

This class will be providing equivalent training for persons who are not CCA's but are pursing CNMP certification through NRCS TechReg. There is a prerequisite web-based course plus this classroom training that will fulfill a portion of the requirements for person's seeking CNMP Total Plan Development certification.

Cost of the class is $150, due by June 15 to MSU Extension, Calhoun County. Contact Sharon Williams at williash@msue.msu.edu or 781-0786 for more information. A full agenda and registration form are available at http://www.maeap.org/education.htm

The course is being held at the Banquet and Conference Center of DeWitt, located off I-69 north of Lansing.

MSU Extension programs and materials are open to all without regard to race, color, national origin, gender, religion, age, disability, political beliefs, sexual orientation, marital status, or family status.

Regional reports

1 - Southeast

Mike Score

Weather
Warmer dry weather has given farmers the break they needed to move this summer's crop production forward.

Commodity reports
In corn, farmers have caught up on planting. Many switched to shorter season varieties to finish up their corn acreage and to fill in spots that suffered from water ponding. Erosion was a significant problem this year. Producers commonly dismiss this year's soil losses to the once-in-a-hundred year rainfall pattern. Weed control still appears to be good to very good. Most farmers are concerned about possible nitrogen losses, however, very few are using PSNT services to calculate the need for additional nitrogen applications.

With warm weather, soybeans are growing quickly. Row canopy closure is just about here. This is a dramatic change from a week ago. Right now most field time is being allocated to planting soybeans.

The wheat crop is finishing right now. There is not much left to scout for from a management perspective. We'll keep an eye out for late season insects. Farmers expect harvest to come about one week early this year. Yields may be on the low side of normal for our region.

In alfalfa, farmers were quick to take advantage of cutting and drying weather. They are glad to be moving onto second cutting. Lodging and insect damage was significant this spring. Almost all alfalfa cutting was delayed to early bloom at the earliest

2 - Southwest

Bruce MacKellar

Weather
Heavy rainfall on the morning of June 10 brought to a close the longest window of opportunity to complete fieldwork since the last week of April in Southwest Michigan. The break in the wet weather did allow many growers to make good progress on finishing up planting soybeans and seed corn, as well as take a shot at harvesting first cutting hay. The warmer temperatures have helped to push both crop and insect development along at an accelerated pace.

Commodity reports
In commercial corn, nitrogen side-dress operations continue. The earliest planted corn is now 18 to 24 inches in height. "Second planting window" corn is 8 to 12 inches, and the latest planted corn is generally 4 to 6 inches. Having corn in three distinct sizes means that there is a wide variety of challenges from insects. The early first two plantings will probably be large enough to be at risk of first generation corn borer larval feeding. Moth flight is on the increase in the area, but there does not appear to be too many egg masses on cornfields that I have scouted at this time. Armyworm has been causing problems, especially in no-till corn or areas adjacent to grassy fields or small grains in Van Buren and northern Cass Counties. See Dr. DiFonzo's article in this issue for more information on armyworm control.

Similar to commercial corn, seed corn is all over the board in terms of crop development. The dry period really helped to get planting finished up. Corn that has emerged looks good.

Soybeans have been behind schedule the most in the region. Substantial acreages of the crop have been recently planted but not yet emerged. Early planted beans continue to look good. There remains some bean leaf beetle feeding, but most fields have limited damage. In fields where substantial amounts of green material was recently incorporated, there may be an increased risk of cutworms and potentially seed corn maggot activity.

In alfalfa, first cutting harvest was fast and furious over the last weekend and early this week. Watch for potato leafhoppers on early re-growth alfalfa.

Some wheat fields were treated for armyworm infestations. The dryer conditions helped to prevent further deterioration of flag leaves from powdery mildew and other fungal leaf diseases. There is an occasional instance of a few heads showing limited signs of fusarium (head scab). In most fields I have walked in, the number of heads infected and the number of kernels affected per head has been very low. Producers may want to increase the air from the fan slightly in their combines to help remove infected kernels.

3 - West Central

Fred Springborn and Roger Peacock

Weather
It has been a good week for fieldwork for most of the region over the past six to seven days. Many growers are again out of the fields, however scattered rains produced three or more inches in the Fremont area and Northwestern Newago County. Other parts of the region received one inch while Montcalm received a few tenths to a sprinkle. Temperatures over the past week have been quite warm: high air temperatures from the upper 70's to the upper 80's F.

Commodity reports
In alfalfa, first cutting harvest is well underway in much of Montcalm and has been progressing in a selective manner in the western part of the region on a field-by-field basis as field conditions have permitted. Alfalfa weevil damage is severe in some fields. Quality is dropping rapidly due to maturity. In the areas that received the storm yesterday, lodging is prevalent. Base 41 GGD totals are well past 750 in all locations in the region.

Wheat has finished flowering for the most part. Lodging has occurred in some fields.

Corn planting is essentially complete in Montcalm, much progress has been made in the late planting or replanting in the last few days. Some of the replanted corn is under water again however. Watch emerged fields for armyworm activity. Early planted fields are variable in stand quality and maturity. The largest is V4.

Soybean planting progressed well, though still behind normal. Dry bean planting has begun

4 - Central

Paul Gross

Weather
Dry weather over the past week allowed farmers to get most of their crops planted. Many of the fields are still wet in many areas and the ground is not working up very well. The light rains the area received on Thursday morning (June 10) will help germination on many fields that have been planted into less than idea conditions.

Commodity reports
The corn crop is planted except for the odd wet field. Most of the early planted fields are looking very good with the warm weather of this past week. Stands are generally good with the exception of areas that have droned out. We are seeing some magnesium deficiencies on some of the sandy soils. Growers are encouraged to take nitrate test this year to determine what happened to the early-applied nitrogen and to assure optimum yields.

The soybean crop is about 90 percent planted. Planting conditions are variable and in some cases poor, but growers are looking at the calendar and planting regardless. With the rains predicted for the next several days, some will look at prevented planting.

Wheat is done flowering in the southern part of the region and is flowering in the northern part. Disease pressure is light for the most part. Wheat growers are advised to scout fields for armyworm. We have not seen any at this time but in years past this pest has caused some problems.

Alfalfa harvest is about 50 percent completed. The yield is good and quality will be determined when forage tests are completed. We are seeing some alfalfa weevil feeding.

Sugar beets are doing much better with the warm weather. Many growers are getting the weeds under control. Stands are average.

There will be dry beans planted this year and several growers are fitting ground and making herbicide applications.

Oats and barley are recovering from a slow start and beginning to look better with warm weather and dry soils. Herbicide applications are being made

5 - Thumb

Mark Seamon

Weather
Scattered rainfall in the past week has kept some growers from fieldwork, but most growers were very busy with catching up on the backlog of work from this spring. Seedbed conditions in many fields were good while other growers pushed the limit on soil moisture levels due to the large number of acres to get across with a late calendar date and forecast for more rain.

Commodity reports
A majority of the first cutting of alfalfa has been harvested. Some of this was baled in good condition while others will be or has been chopped. The short hay crop last year made this good yield even more welcome this spring.

Crop growth has been very good in sugar beets in the past week. Many recent replants are emerging nicely and will hopefully fill in areas with poor stands.

The corn crop across the Thumb is more variable than I have ever seen. We have a few great looking early-planted fields and some fields that have just been planted. But most are somewhere in-between with problem areas. These problem areas have been caused by standing water, extended saturated soil, compaction, fertility, and many combinations of these. A return to good growing conditions with sunshine and warm temperatures will greatly benefit these fields.

Most wheat has completed flowering as of this week. Hopefully the limited rainfall during this past week of peak flowering will have eased some of the head scab pressure. Armyworm infestations have been found in a few fields above threshold, but most fields have a limited population. Keep a careful eye on wheat fields for armyworms and feeding. Cereal leaf beetle can be found in many fields also, but populations and leaf feeding are limited. Powdery mildew and septoria are making use of the high moisture conditions under the canopy but are not spreading much to the upper leaves of the plant.

Soybeans have had a great planting effort this past week. A majority of this crop has been planted in the past 10 days. Some fields had a lot of weed growth prior to planting and may be an issue with weed control if these weeds aren't considered when applying post emerge herbicides

6 - Northern Lower Peninsula

Dave Glenn

Weather
Great weather has aided planting of most crops. We went from 94 degrees to 40 degrees in a day. Small rains have not stopped most fieldwork. Some of the wetter fields are working up cloddy and may pose some problems at harvest in potatoes and dry beans.

Commodity reports
Corn is starting to green up with the warmer weather. Most corn is now planted, so there will be a lot of variation in maturity come fall.

Wheat is about four to seven days from heading. Powdery mildew has not been a problem yet this year.

Soybeans are emerging quickly with the warmer weather. Stands look pretty good so far.

Dry bean planting started late last week and has been steady all week. Most planting should be completed by the end of the week. The plot was planted on June 9 for MSU under ideal conditions.

Cutting of hay and alfalfa has started with variable yields and quality. Grasses and dandelions are heavy in older fields. First cutting for most dairies will be started by the weekend.

Rye is headed out, but looks thin this year. Oats and barley are looking very good with ideal conditions for small grains this spring.

Weather news

Jeff Andresen
Agricultural Meteorology
Geography

With a broad upper air ridge in place across the Great Lakes region and a steady northward influx of moisture from the Gulf of Mexico, an extended period of wet weather is in store once again for at least portions of Michigan during the next few days. The weather system has already led to the formation of strong thunderstorms that brought torrential rains (2 to 6 inches), flooding, and large hail to sections of the central and southern Lower Peninsula Wednesday (June 9).

On Thursday morning, a nearly stationary frontal boundary stretched from low pressure over the central Great Plains eastward to near the Indiana/Ohio/Michigan border to New England. As has been the case for the past one to two days, the front will continue to act as a general focusing mechanism for showers and thunderstorms as it meanders back and forth across the region during the next couple of days. Given ample low-level moisture already in place just to the south of Michigan, heavy rainfall will be a possibility in some locations through Sunday. While rain will be possible on an almost daily basis in at least part of Michigan through Sunday or early Monday, the greatest likelihood will be in southern sections of the state, where some 1- to 2-inch rainfall totals are a good bet. Rainfall amounts and areal coverage will decrease northward into the Upper Peninsula, where best chances for rain will be overnight Friday into Saturday. Temperatures will fall back to near or slightly below normal levels during the next few days with highs and lows generally ranging from the 60's north to the 70's or low 80's south and upper 40's to upper 50's. A relatively cool and unsettled weather pattern with an almost daily chance for afternoon/evening showers is a good bet for the middle to latter part of next week.

Further ahead, medium-range forecast guidance suggests the formation of an upper air trough across the eastern US and a ridge across the Rocky Mountain and High Plains regions. The 6-10 day outlook, covering June 15-19, calls for near normal temperatures statewide, and for precipitation totals to vary from near normal over northwestern sections of the state to above normal in the southeast. For the 8-14 day time frame covering June 17-23, the outlook calls for temperatures to range from near normal in the southeast to above normal in the northwest and for above normal precipitation totals statewide.