Northeast Michigan field crop update – July 7, 2017

Growers welcomed the recent dry weather.

Weather and rainfall

A total of 1.33 inches of rain fell during eight wet days at the Hawks Enviroweather station since June 22. All but 0.15 inch of that rain came during the last week of June, which was in stark contrast to a relatively dry first week of July. A total of 10.46 inches of rain has fallen at Hawks since April 1, which is 2.9 inches above the five-year average for this period.

Growers welcomed the recent stretch of dry weather, which allowed progress with previously delayed field operations, such as hay mowing and spraying. Our next chance for precipitation will come July 9 with a 40 percent chance of scattered showers.

The National Oceanic and Atmospheric Administration (NOAA) 6-10 day outlook predicts above normal rainfall for the coming week, while the 8-14 day outlook suggests below normal rainfall amounts for the following week.

Growing degree-days (GDD)

Daytime high temperatures ranged from 67 to 87 degrees Fahrenheit over the last seven days, with overnight lows between 45 and 60 F. GDD accumulations since March 1 total 2,209 base 32 F, 1,368 base 41 and 741 base 50.

Northeast Michigan ranges from three calendar days behind to three days ahead of the 30-year average for GDD accumulation in our region. High temperatures are expected to remain in the mid to upper 70s over the next seven days with mostly sunny skies. The NOAA 6-10 day and 8-14 day outlooks are predicting above normal temperatures in coming weeks.

Commodity reports

Harvest of first cutting alfalfa and mixed hay progressed rapidly over the July 4 weekend and following week. Growers had been waiting for the forecast to clear before cutting for dry hay, which put them approximately one to two weeks behind schedule.

A heavy downpour during the afternoon of July 6 moistened cut and baled forage left to cure in many fields and also further delayed harvest activities. On the bright side, forage yields have been impressive thanks to plenty of precipitation. Quality of grass hay will continue to decline rapidly as harvest is further delayed. However, alfalfa is still only in mid-bloom, suggesting quality of recently harvested stands will be strong. Timothy grass is flowering.

Winter wheat in northeast Michigan is in the grain-fill stages (mostly late milk) and beginning to change color. Stands with adequate fertility, and where foliar diseases were controlled, are staying green longer and extending grain fill.

Symptoms of Fusarium head blight have been observed in many fields as single, partially bleached heads, in some cases showing pink to orange spikelets. This is not surprising, given our wet weather during flowering. However, prevalence is mostly less than 1 percent of heads infected. Michigan State University Extension advises scouting wheat fields for scab and adjust combine settings accordingly to remove scabby kernels during harvest.

We have also noticed patches of entirely dead, white plants in many fields. These bleached heads can easily be confused with Fusarium head blight, but appear in this case to be caused by other fungal pathogens like take-all that infect the base of the stem restricting the flow of water and nutrients to the developing head.

A way to distinguish between Fusarium head blight and other causes of bleached heads in wheat is to note the extent of bleaching on the heads and across tillers on a single plant. Bleaching caused by Fusarium head blight is often restricted to only a portion of each head or a subset of heads on a plant, while other diseases terminate the entire plant early resulting in entirely bleached heads on every tiller that often fail to produce seed. Wheat harvest should begin in approximately three weeks.

Spring oats and barley are heading.

The corn crop in our region ranges from V6 to the V9 growth stage. Most fields met or surpassed the traditional “knee high…” benchmark. Heavy rains during the last week of June led to standing water on poorly drained soils, which stunted corn. There is now significant variability in crop condition within some fields, as a result.

Growers are applying sidedress nitrogen after waiting for fields to dry out. Second herbicide passes are also being made, especially where excessive rain encouraged a new flush of weed growth. V8 is the cut-off point for glyphosate applications in corn, and some growers are rushing to get herbicide on in time. European corn borer and earworm numbers remain low. Stink bugs have been spotted in the field, but no significant injury was observed.

Soybeans in the northeast have three to five fully emerged trifoliate leaves, and some are beginning to flower. Fungicide applications for white mold should be made during bloom on fields with a history of this disease. The numerous small brown lesions indicative of Septoria brown spot are becoming evident on the lower leaves of some plants. Soybean aphids were observed for the first time this week, but numbers remain low.

Now is an excellent time to check nodulation on soybeans. Inoculation failure is often an issue on new soybean ground, but can occur elsewhere. Plants should be dug rather than pulled to judge nodulation, and a minimum of seven pink-centered nodules 2 millimeters or greater in diameter is considered acceptable.

Nitrogen deficiency can also occur on marginal soils with low organic matter or high residue, despite good nodulation. This is indicated by light green across the entire surface of the newest trifoliates. Fields with poor nodulation, or nitrogen deficiency confirmed by tissue analysis, should receive 60-70 pounds of actual nitrogen as ammonium nitrate, stabilized urea or 28 percent applied using streamer bars or drop nozzles.

Early planted potatoes are beginning to develop buds, and in some cases flower. Tuber initiation is also underway, with daughter tubers 0.25 to 1.5 inches in diameter. Hilling and sidedress fertilizer application has continued in the last week.

Colorado potato beetle larvae are in their second instar on susceptible plants and nightshade weeds. Consider foliar insecticide applications in certain areas. Leafroll and mosaic virus-infected plants are becoming more obvious, particularly in fields planted with saved seed. Rhizoctonia stem canker can be observed on dug roots and stolons, but pressure appears limited overall.

Dry beans in our region have two to four trifoliate leaves and condition of the crop is improving with time. The first cultivation pass has been made in most fields, and weed control appears to be good overall. Symptoms of root rot are showing in isolated areas, with yellowing leaves and roots declining rapidly. Yellowing of plant tissue may also be due to limited root development under wet conditions, or nitrogen loss following excessive rainfall. Some growers are applying supplemental nitrogen to compensate.

Only one western bean cutworm moth has been trapped at our monitoring sites in the northeast, but their flight is picking up rapidly downstate.

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