West central regional report on Michigan field crops – August 23, 2012

Japanese beetle and potato leafhopper numbers are declining, while spider mite populations have disappeared.


High air temperatures ranged from 73 to 84 degrees Fahrenheit this week. Lows were in the mid-40s to mid-50s. Soil moisture conditions are generally adequate with the far western and southern portions of the region being the driest. Rainfall for the past two weeks has been variable with the west edge of the region receiving the lightest amounts of 1 to 2 inches while the Montcalm and southern Mecosta area received 3 to 6 inches for the two-week stretch, much of that falling on August 9 and 10.


The majority of the corn crop is in the late milk stage to early dough stage with a few fields at dent. We are monitoring fields for ear diseases, but have found little of concern at this time.

Soybeans are filling pods. Dry beans are starting to turn. We are still some time away, likely a week or more, from the start of dry bean harvest. I hear a lot about Japanese beetle feeding, but have yet to see any that is near the control threshold of 25 percent defoliation. In field crop production, we tend to have annoying levels of Japanese beetles, but we tend not to have threshold levels. Most of the damage looks far worse than it actually is. In addition, Japanese beetle adults are nearing the end of their life span and numbers are already declining.

Spider mites are dead. Cooler and wet weather with higher humidity has enabled fungal pathogens that have crashed the population.

Potato leafhopper numbers are down to levels that are generally below threshold and are expected to continue their decline as we head into more fall-like weather.

Alfalfa cutting is progressing this week as many producers take third or fourth cutting. Overall, yields are expected to be low for the season with many producers expecting to have 1/2 to 2/3 of their normal hay and haylage inventory.

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