Regional reports on Michigan field crops – July 26, 2012

MSU Extension educators’ pest and field crop updates for Michigan.

This week’s regional reports:

Southwest Michigan – Bruce Mackellar, Michigan State University Extension

Southwest Michigan
Southwest Michigan

Conditions

There is nothing like a significant and widespread rain following a prolonged period of drought to help raise grower’s spirits. Southwest Michigan finally received a rain on the evening of July 18-19. With precipitation totals ranging from 0.75 to over 2 inches, it was the first significant rain that many areas had seen since the crops were planted in early May.

How much will the rainfall help the crops? Well, the answer depends on many factors: soil type, slope in fields, the tracks of thunderstorms, rainfall received and development stage of the crop when the high temperatures were seen following the July 4 weekend and when the rain fell last week. All of these factors play a huge role in the conditions of crops in the fields.

In general, the worst hit areas in terms of the drought in the southwest region are northern Berrien County, central Van Buren and Cass counties, southern Kalamazoo and Calhoun counties and various droughty tracks in St. Joseph and Branch counties east over to I-69. I have not been much farther to the south and east Michigan during the last few weeks. Within this area, we have quite a few dry land corn fields on predominately lighter ground that will not produce economic yield. We have been discussing the potential to salvage value out of these fields as corn silage. Fields that were planted a little later, or saw more rainfall or were on heavier ground, may produce highly variable corn yields that may average something around 35 to 45 bu/acre if we can avoid further stress. If an area had any moisture to work with at all, yields may be 50 to 80 percent of normal.

Irrigated corn and muck corn looks really good, with potential for extremely high yields if there was adequate moisture during the high heat periods. Soybeans have had less damage than corn. Although the plants are short, they have begun to respond to the moisture and add top-growth, setting new pods and flowers, and shaping up. The worst stressed areas and the lightest portions of fields suffered widespread loss of lower leaves and even had pockets of high plant loss due to the drought stress. Most fields have some damage, but are not as likely to suffer total loss as compared to the worst hit corn fields. Rain showers on July 23 and 24 added to rainfall totals, allowing for favorable recovery and stress reduction.

Outlook

The heat is back on in the 6-10 day outlook, with temperatures expected to remain in the above normal range for that period. NOAA has the region in a moderation period in the 8-14 day outlooks, with near normal temperatures. The growing degree day total for inland areas is around 1,620 since May 1.

Rainfall

Dare we hope for a real break from the drought conditions? Both the 6-10 and 8-14 day outlooks have the region in the above normal precipitation range for these periods. However, we have seen this in the forecast before this season with little precipitation to show for it. For more information, see meteorologist Jeff Andresen’s Michigan drought update for July 25, 2012.

Crops

The summary of the dry land corn crop condition is provided above. Advanced irrigated corn fields are through pollination and are heading for R2. Western bean cutworm egglaying has dropped off. Scout non-protected fields for larvae if you had not seen egg masses. I have not seen much for corn leaf diseases on commercial corn yet, but there were a few plants in southern Berrien County that were showing signs of northern corn leaf blight. Irrigators should evaluate the soil moisture levels carefully to make sure there is adequate moisture in the soil following the rainfall. ET rates are still quite high through early grain fill.

Excess nitrogen is on drought-stressed, dry land corn. We do have a window of opportunity to perhaps fly on a cover crop to utilize some of the nitrogen applied to corn that will not reach it’s intended yield goal this year. The plants are shorter this year, which will allow for more sunlight to reach the ground. This will most likely also spur weed growth, particularly where soil active herbicides were not applied or were applied at lower rates with post-emergent glyphosate applications. A cereal cover crop or wheat or rye can help to be competitive with weeds and absorb some of the excess nitrogen that remains in the field.

Soybeans are looking better following the rainfall. We need to be careful to not overlook spider mites in both dry land and irrigated soybeans. I have seen lots of "blow in spots" in fields, small pockets where stippling and yellowing are occurring.

Watch for small, roundish yellowing spots when walking though soybean fields. If you treat for spider mites, remember that the eggs laid in the fields will not be controlled by the insecticide you use. See MSU’s recommendations for spider mite control.

I am also concerned that we may be setting ourselves up for a potentially explosive white mold infection period on irrigated fields or fields that have received rainfall over the past few weeks. Unfortunately for us, the rainfall we need to help reduce the threat from spider mites may be enough to trigger white mold issues in heavy growth soybeans.

Soybean aphid numbers dipped after we saw the high temperatures in early July. Aphids can rebound if we see more moderate temperatures and softer conditions return. Soybean cyst nematode high infestation areas have suffered worse from the drought stress and are remarkably visible in fields. It may be a good year to identify areas in fields and investigate if the variety you planted had PI-88788 resistance, which may indicate it’s time to investigate other sources of soybean cyst nematode resistance in the beans you plant.

Early onset of sudden death syndrome is visible in a few fields I have walked. Watch for more development in the second and third week in August.

Alfalfa is beginning to grow again after the rainfall. Some people clipped the third cutting to spur growth when rainfall returned. With rainfall in the forecast, we might be setting the stage for a good late cutting. Watch for leafhoppers, which have been extremely variable across the region this year. Forage and pasture is at a premium, especially across southwest Michigan. There have been several inquiries about harvesting CRP and idle lands for low quality winter forages. Be sure to look for poisonous weed species such as poison hemlock, hoary alyssum, black nightshade, and jimson weed.

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West Central Michigan – Fred Springborn, Michigan State University Extension

West Central Michigan
West Central Michigan

Weather

Scattered rain and thundershowers over the past two weeks have brought at least temporary relief to field crops across much of the region. High air temperatures ranged from the low 70s last Wednesday (July 18) to the upper 80s toward the end of the week. Low air temperatures were in the upper 50s to mid-70s. All unirrigated areas still have soil moisture deficits down through the soil profile in the lower root zone.

Crops

Corn ranges from tassel emergence to blister. I continue to rate the overall condition of the corn crop in the region as fair where irrigation is not available. There are certainly plenty of examples of poor and very poor corn crops, especially in the southern portion of the region, including the southern edge of Montcalm County across into southern Newaygo County. However, there are also many areas that will have an OK crop.

Now that we are past pollination we can start to more closely evaluate this crop, which will not be an easy task. Fields are highly variable and sorting out the variability will be one of the big challenges. Continue to monitor soil moisture carefully in irrigated fields over the next few weeks as most fields do not have much subsoil moisture to spare.

Most alfalfa producers have finished second cutting. Potato leafhopper numbers will need to be monitored.

Dry beans are blossoming and setting pods. Western bean cutworm adults caught in pheromone traps have decreased, but we are still getting some flight. Egg masses have been difficult to find in corn this year with many egg masses showing signs of pathogens of parasitoids. Weather conditions have been less than favorable for egg deposit this year. Continue scouting fields for potato leafhoppers, also start looking for blossom and pod damage in areas that have had a history of western bean cutworm damage. The timing for insecticide applications to control western bean cutworms will be the first few days of August this year, but remember that it is better to be a little late if control is needed than to be too early.

blossom damage pod feeding
Western bean cutworm damage to blossom (left) and pod (right).

Soybeans are blossoming and setting pods in many fields. Very low numbers of aphids are present. Spider mite damage is increasing in drier parts of the region.

Oat harvest is underway.

Corn ear worm adults are also being caught though the numbers are low.

Japanese beetle adults are present in corn, soybeans and dry beans as well as other crops. So far the numbers are interesting but not threatening to these crops. This is an insect worth monitoring.

Japanese beetle
Japanese beetle feeding on soybean leaf.

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Central Michigan – Paul Gross, Michigan State University Extension

Central Michigan
Central Michigan

Weather

Rains overnight (as of July 26) brought some much needed relief across the region. Rainfall amounts varied, but most areas received 1 inch or more. This is a just-in-time rain. Most crops in the region have been holding their own because the center part of the state has received rains when others have not. The extreme heat over the past two weeks has caused some pollination problems. The region is in the critical grain fill period for corn so this rain will aid in what most farmers hope will be a near average crop.

Commodity reports

The corn crop is nearing the end of the pollination period for most of the crop. Pollination has been less than ideal. The early observations indicate that about 2 percent of the kernels did not pollinate. It is expected that the percentage that did not pollinate is much higher in some fields. Some of the later planted fields are just entering pollination, so this week’s rain and cooler temperatures will be a great benefit. Some corn on the coarse-textured soils has been hurt by the dry conditions and yields will be well below normal.

Soybeans will be the big winners with today’s rains. The crop varies widely in growth stages. The early planted soybeans are in R4 while later planted fields are at R2.There is a concern that we may have lost many flowers and pods in the lower nodes. Spider mite populations are very high in some fields and have been sprayed. Continue to scout fields for this pest. There have been no reports of any soybean aphid problems. Some root and foliar diseases have been showing up in scattered fields.

Wheat harvest has wrapped up with most reporting good yields. It will be important to control weeds in these fields after the rains. Many farmers are putting cover crops on these fields. Farms that have sold straw off the wheat fields should consider a cover crop to replace the organic material. Building organic matter should be a long-term goal on every farm for long-term sustainability.

Oat and barley harvest is wrapping up with most farmers reporting average yields.

Harvest of third cutting alfalfa is wrapping up for farms on aggressive cutting schedules. Yields are below average due to the dry conditions. Potato leafhopper populations are above threshold in most fields. Scout for this pest. Pastures and grass hay fields have dried up with little to no production. Summer seedings are being planted.

Dry beans are flowering and beginning to set pods. Scout these fields for leafhoppers and monitor the western bean cutworm traps to determine if and when insecticide applications will be needed.

Sugarbeets are holding their own with the dry conditions.

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