Cotton fleahoppers are in most fields. Grasshoppers are an increasing as well.
The fleahoppers are most concerning because we are just on the verge beginning to square across many acres. We cannot afford to lose any early squares since we don’t have time to compensate as we might have in previous years.
Many of these fleahoppers may currently be interested in some weed species, like whiteweed (aka silverleaf nightshade). As we attempt control of many of these weeds as weather is allowing it will force the fleahopper to the young cotton, causing loss of squares.
Cotton ranges from 2 true leaves to 11 true leaves, with match-head size squares. Square set is good (+90%) in those fields which are squaring (<10%). A few fleahopper induced square losses have been noted in a couple of fields to date and those are being treated. I would like to see most fields squaring by this time next week so it will give the fields time to begin blooming before the end of July.
Management and decision making.
The decision to apply insecticide should be based on the number of fleahoppers present, the squaring rate and the percent square set. If conditions are conducive to the rapid buildup of cotton fleahoppers in alternate hosts, scouting intervals should be shortened (i.e., monitor fields every 3 to 4 days).
During the first week of squaring, the economic threshold is 25 to 30 cotton fleahoppers per 100 terminals combined with less than 90 percent square set. In the second week of squaring, the economic threshold is 25 to 30 cotton fleahoppers per 100 terminals combined with less than 85 percent square set. Starting with the third week of squaring up to first bloom, the economic threshold is 25 to 30 cotton fleahoppers per 100 terminals combined with less than 75 percent square set.
As plants increase in size and fruit load, larger fleahopper populations can be tolerated without yield reduction. In most years treatment is rarely justified after first bloom. However, occasionally, when cotton plants do not set an adequate square load during the first 3 weeks of squaring, fleahoppers can prevent the square set that is needed for an adequate crop
Most peanuts are blooming now. No worm feeding damage has been noted to date, though various moths and millers are working the fields. Weeds are priority for most, followed by getting fertilizer going and water started. Many want to cultivate, which is a very good idea before peanuts run and or peg. Just be careful not to pitch soil to the crown of the plant. Soil covering the crown can increase incidence of pathogens in that area.
My priority list for this week is:
- Fertility -what will it take to achieve a realistic yield goal? Seize the moment to fertilize. Do not delay, as it only delays the crop and can lead to disease and other pest problems.
- Irrigation -most plants have rooted as well as they can, do not stress these cotton plants as they move into squaring, you can induce square shed. So, irrigate if you do not receive a rain.
- Weed control – hopefully you have your applications of a post-emerge plus a residual herbicide out to carry us through July.
- Plant map – what is the plant telling you? Will it need a plant growth regulator (believe it or not we have cotton that needs a PGR).
- Insect scouting – never let your guard down, watch fleahoppers in cotton.