Northeast Michigan field crop regional report – July 3, 2014
Growers hope for heat to push crops along.
Weather and rainfall
This week, like last, began with a little rain. A band of storms moved through midday Sunday, June 29, dropping 0.26 inches in the course of two hours. Total rainfall for the month of June at the Hawks Enviro-weather station was 2.48 inches, approximately 1.20 inches below the five year average. Sunday’s storm was not enough to reverse the current downward trend in soil moisture levels, but it did improve crop condition on excessively drained soils. Scattered showers dropped 0.04 inches this Tuesday night through Wednesday morning. More significant rain is in the forecast for early next week, beginning with light rain Sunday, July 6 that could develop into thunderstorms by next Monday evening. The 6 to 10 and 8 to 14 day outlooks from NOAA indicate that precipitation totals should be near normal in coming weeks.
Growing degree days (GDD)
High temperatures over the last week ranged from 68 to 90 degrees Fahrenheit with lows between 47 and 67 degrees F. Warmer days last weekend, paired with a little rain, generally improved crop condition. GDD accumulations since March 1 total 1,888.1 base 32 F, 1,174.6 base 41 F, and 645.3 base 50 F. Most of Northeast Michigan is now on track with the 30 year average for this point in the season. Despite a slight decline in temperatures this Tuesday and Wednesday, a large area of high pressure is expected to build into our region beginning mid-week, bringing clear skies and highs in the mid-70s. That warming trend should continue into next week, with daytime highs reaching 80 degrees F by Tuesday, July 8. The 6 to 10 and 8 to 14 day outlooks from NOAA suggest that our region will likely experience near to slightly above normal temperatures over the next few weeks.
Most winter wheat in our region has finished flowering and is now entering the grain fill stage of growth (Feekes 10.5.3-11). Grain fill and ripening can last as long 35 days under ideal conditions, but is often shortened by environmental stresses like heat and drought. Because kernel size and weight are determined during this stage, a longer grain fill period usually results in higher yields. Moderate temperatures and near normal precipitation levels expected over the next few weeks should limit plant stress and maximize grain development.
The risk for Fusarium head blight (scab) has remained low in Northeast Michigan this season, except along the shore of Lake Huron near Thunder Bay and Tawas Bay. No cases of scab have been reported thus far. However, what appears to be Stagonospora glume blotch, another fungal disease, was observed in the field. Symptoms of Stagonospora include dark brown to purple lesions near the top of the glume, with streaks or blotches extending down to the base of the spikelet. Scab, on the other hand, generally produces bleached spikelets containing pink to orange masses of spores.
Most forage producers in the Northeast have harvested their first cutting of dry hay. Some lower quality grass forage remains standing, but alfalfa is baled and ready to be stored. Very little curing hay remained in the field over the weekend as rains moved through. However, a great deal of baled material was exposed to short-lived downpours Sunday, June 29. Alfalfa weevil pressure remains relatively low, but increased feeding may be seen on new regrowth. An insecticide application is warranted if feeding damage is apparent on 50 percent of the regrowth and/or more than six weevils are found per square foot. The earliest sown spring seedings are five inches tall and oat nurse crops are heading.
Corn in our region ranges widely in development from the three-leaf to seven-leaf stage (V3-V7). Interveinal chlorosis, an indication of sulfur, zinc or manganese deficiency, is becoming more apparent on sandy soils where organic matter concentrations are low. The symptoms observed appear to be mainly manganese related. Some of the symptomatic plants may improve with increased root growth and nutrient cycling. Otherwise, timely application of 0.5 to 2 lbs per acre foliar manganese, either as chelated Mn or manganese sulfate, can correct the problem. Producers are beginning side-dress nitrogen applications in early planted corn. Deer feeding is evident in most fields, ranging from slight leaf damage to complete destruction of individual plants.
Soybean development remains highly variable, but earlier planted beans now have a partially developed fourth trifoliate leaf. Early symptoms of Septoria leaf spot are becoming evident on lower leaves following recent rains. Occasional soybean defoliators, including alfalfa weevil and green cloverworm larvae, are impacting this year’s crop. Damage by these relatively minor pests rarely reaches the economic threshold of 40 percent defoliation prior to bloom. Most observed feeding injury has been in the range of 5 percent to 10 percent defoliation. Green cloverworm populations are frequently controlled by naturally occurring parasitic insects and fungal pathogens. However, alfalfa weevil can feed on soybean stems as well as leaves, permanently damaging young plants. Growers are encouraged to note damage by these minor pests when scouting for more common defoliators, as combined injury may exceed treatment thresholds.
Potatoes have sprouted and producers are beginning to cultivate and inject fertilizer as weather permits. Now that first-cutting of forage is well underway, potato leafhoppers will begin to migrate into potato fields. No late blight has been reported in Michigan, but our region is now in the moderate “yellow zone” for disease risk. Therefore, Michigan State University Extension recommends the highest labeled rate of a protectant fungicide be applied every seven days. Several late blight cases were confirmed in Michigan’s 2013 potato crop after two years without the disease. According to MSU potato pathologist Willie Kirk, “The first symptoms of late blight in the field are small, light to dark green, circular to irregularly-shaped, water soaked lesions. Lesions usually first appear on the lower leaves where the microclimate is more humid, and often begin to develop on the compound leaf near the point of attachment to the petiole.”
Dry beans across our region are developing their first or second trifoliate leaves. Earlier planted fields on well-drained soils are being cultivated for weed control. Crop condition is overall good to fair, but herbicide injury and deer feeding appear to be taking their toll in certain areas. Dry beans are not genetically modified for herbicide tolerance and generally more prone to herbicide injury than common field crops. Weather conditions during herbicide application and crop emergence predominantly determine the severity of injury. Luckily, dry beans are also flexible and can grow out of minor injury that occurs early in the season. Deer, however, tend to nip dry bean seedlings, removing the apical bud and effectively terminating the plant.