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This is Jack Bacheler, Extension Entomologist at NCSU with the Thursday Cotton Insect Update. Today is Thursday, June 26.

Despite still being short on moisture in most areas of the state, cotton is still coming along reasonably well, with most of our crop probably in the fair to good category, though a bit behind due to cool spring temperatures. With some luck, blooming will be underway in a few cotton fields by early to late next week. For most cotton fields, bloom initiation will be after our July 4 standard.

False chinch bugs have been showing up in somewhat higher numbers than in the past few years. These are about the size of plant bugs but, where present, occur in far higher numbers and for the most part do only minor economic damage to cotton and soybean seedlings. If you’re accustomed to plant bugs and their quickness, false chinch bugs are far slower. An initial exposure to this insect can be frightening; sometimes hundreds or even thousands may be present in a square meter. They tend to move in from field edges, but can be present throughout reduced tillage fields that still have plenty of refuse from the previous year’s crop. Treatment for false chinch bugs is not generally recommended as economic damage is uncommon and control is often poor to mediocre. 

Plant bugs have approached economic thresholds in scattered cotton fields, primarily in the far eastern counties. If upper squares are retained at over 80% with no evidence of blackened squares in the terminals, additional more detailed assessments like ground cloth or sweep net sampling are not needed at that time. If very small blacked squares are noted along with square retentions less than about 90% I’d look further, probably with a sweep net. One consultant yesterday reported a few fields in which the square retention was still well above 80%, but blackened squares were present. Sweeping revealed over 20 plant bugs per 100 sweeps, or about 2.5 times the recommended treatment threshold here. As far as we know, plant bug resistance to the insecticides listed in the 2008 NC Agricultural Chemicals Manual has not occurred here, so all of the materials listed should work. Although very active against plants bugs, all of the listed materials except for the chloronicotinoids like Trimax Pro and Centric are disruptive and may increase the odds of cotton aphid and/or spider mite outbreaks, particularly following a prior application of Orthene. Generally speaking, but not always, plant bugs gravitate towards lusher cotton fields.

A few spider mite outbreaks have also been reported in eastern NC. Economic levels of spider mites are not fun to deal with, as they are often hard to kill with expensive materials, and sometimes require a second application. Kelthane (now sold a dicofol) has been our old standby and still performs well, even compared to the newer materials like Oberon and Zeal. However, the effectiveness of these materials in tests conducted throughout the cotton belt varies greatly. Because of our generally high humidity and the possibility of a fungus coming to the rescue, we generally regard a mite population as treatable when leaf discoloration (such as yellow speckling or bronzing) and live mites are present in 25% or more of the field. If rain is immanent, delay the application and reevaluate 3-4 days after the rain.

Our initial Hoke/Robeson/Scotland county area Cotton Scouting School will be held this coming Wednesday, July 2 in the Scotland County Extension office in Laurinburg.

It’ll be interesting to see how spider mites and plant bugs unfold during this next week.

We’ll see you next Thursday, July 3.