If farmers are looking for another reason to take their first cutting of alfalfa fairly soon, it would be that their fields are infested with enough alfalfa weevil larvae to degrade both the yield and quality of the crop.
Buildups of the pest's population were helped during the wet weather during the first part of May, according to the second weekly edition of the Department of Agriculture, Trade, and Consumer Protection's Pest Bulletin for the month.
It noted that in southern parts of the state the weevil's development had reached the quite damaging 3rd and 4th instar stage.
That the infestation of the weevil is probably widespread was indicated in a report from Manitowoc County, based on observations by crop consultants, that there was "higher than normal pressure" in the standing alfalfa - much of which they recommended for cutting within a few days.
The Pest Bulletin recommends an insecticide treatment if tip feeding damage has reached 40 percent and the anticipated harvest is still 7 to 10 days away.
Once the first cutting of alfalfa is taken, the regrowth could be vulnerable to feeding by migrant potato leafhoppers, the Pest Bulletin indicated. Migrants were found as far north as Monroe and Manitowoc counties.
Moderate populations were found in 19 of the 29 fields in Dane, Green, La Crosse, Rock and Monroe during the latest reporting period.
Nymphs were already found in Lafayette County.
A secondary concern with potato leafhoppers, which thrive in warm and dry weather, is how they will seek other plant hosts such as snap beans and potatoes after an alfalfa cutting is taken.
Economic loss thresholds in those other crops are .5 to 1 leafhopper caught per net sweep.
Meadow spittlebugs and their foamy masses were also appearing in alfalfa fields. Pea aphids were being caught at the rate of 2 to 6 per net sweep.
The wet conditions in many corn fields, along with early growth of annual weeds, have been especially favorable for black cutworm larvae, which are the progeny of very early moth flights this spring, the Pest Bulletin reported.
It expected that plant cutting, often right at the soil surface, began on emerged corn in southern regions this week and urged crop scouts to check for outbreaks.
Corn with Bt traits is not immune to black cutworm damage, the Pest Bulletin warned. It listed economic damage tolerance limits of 3 percent of corn and leafy green plants, two larvae per foot of row for snap beans, and four larvae per foot row of potatoes.
European corn borer moths were caught in a black light trap on the night of May 1 at Coon Valley.
Entomologists expect, however, that moth flights won't peak until May 29 in the south, June 6 in the central region, and mid-June in Wisconsin north central and northern counties.
Another early arrival record for a crop pest - the corn earworm - was set during the first week of May with the catch of 28 moths at a trap at Prairie du Chien and another at Janesville.
Heavy flights of corn earworm moths were reported in Texas and Arkansas. In Wisconsin, the good news about the early moth flights is that no corn would be close to being advanced enough to accommodate the pest.
More ominous is the discovery of the fifth brown marmorated stink bug in Wisconsin - this time at a residence in Jefferson County, which joined Brown and Dane counties as having an apparent minimal population of the pest that has been ravaging fruit and vegetables in northeast states for the past few years.
For the moment, the good news about this pest is that no verification has been made so far of an established population in an agricultural setting.
Given the high number of catches of true armyworm moths in black light traps during recent weeks, entomologists are concerned about potential larval outbreaks in small grains and corn.
However, there had not been any reports of larval infestations to the Pest Bulletin by May 10.
Because of the likelihood of the establishment of soybean aphid populations again this summer, the Pest Bulletin is looking for volunteers to take two to three counts in fields from June to August in Columbia, Dane, Dodge, Green, Iowa, Jackson, Jefferson, Lafayette, Manitowoc, Richland, Rock, Sauk, and Walworth counties.
To volunteer, send an e-mail to email@example.com
or call 1-866-440-7523 by June 1.
An earlier concern with soybeans and other bean crops is the observed overwintering of adult bean leaf beetles in at least Dane, Rock, and Lafayette counties. The pests are attracted to the earliest planted beans, on which they chew holes in the leaves.
In line with the year's early movement of pests, migrant spotted cucumber beetles have already been detected in the southern half of the state, the Pest Bulletin reported. They are threats to melons and cucumbers.
Colorado potato beetles were also beginning to lay eggs by mid-May.
A concern for fruit owners is the documented flight of codling moths at 17 of 29 surveyed orchards with the highest count being 14 months in a trap at Deerfield in Dane County.
The Pest Bulletin noted that cold and windy nights are good because they delay the hatching of the codling moth egg masses, rendering them unviable.
The year's second flight of the spotted tentiform leafminer was expected very soon in the southern area. The orchard pest typically has three moth flight periods per season.