While it has been a miserable week of high heat for hardworking producers and field scouts, it has been a needed week of recovery for our late or damaged crops. For our most recently damaged fields, it was a week of decision.
Several fields in western and southwestern Hale were lost to weather events of last week. Planning (sometimes with plan C or even plan D) and re-planting are fairly common in the impacted areas. We expect quite a few acres will go to a late corn or sorghum option while some others might be left as layout for the summer, possibly to be planted as wheat in the fall.
For the crops recovering, we are seeing some major progress in the right direction. The high heat has brought plenty of heat units while most areas still had soil moisture to propel these crops forward.
Producers are making great headway in managing these crops, the pests attacking them, and the weeds robbing them. The heat has also ignited most of our irrigation systems in our corn crops and in our drier areas for all crops.
The thrips pressure in our program fields really dropped off this week following treatments, a conclusion to most wheat harvest, and several fields developing past economic thrips damage. We still have many fields at risk for thrips injury that are already moderately late and we will be watching them closely to prevent thrips damage from delaying them farther.
Our program thrips counts ranged from 0 per true leaf up to 1.12 thrips per true leaf with most falling under 0.2 thrips per true leaf. Fields will remain at risk for thrips damage until pinhead square stage with an economic threshold of 1 thrips per true leaf stage.
The next pest we will be, and in several cases, already are dealing with in cotton is fleahoppers. Fleahoppers have several preferred host but these guys primarily feed on silver leaf nightshade (SLN) and jump to nearby cotton once the silver leaf nightshade has been destroyed by herbicide or tillage.
Fields heavy with SLN are much more likely to develop economic problems with fleahoppers than those without. Adults are about 1/7th of an inch long, extremely flighty, and pale green to greenish white in color. Nymphs of this true bug are smaller than the adult, lack wings, but are otherwise very similar.
Fleahopper nymphs may appear similar to the nymphs of a freshly hatched Lygus at first glance, but the lack of prominent dark spots on their backs and their slightly ‘grasshopper-like’ hind legs give them away. Because Lygus are potentially much more economically damaging and not all cotton labeled insecticides will control both pests, identifying which pest is present in your field becomes very important.
Even though cotton is only a secondary host for fleahoppers they will can cause significant yield loss if present at economic levels. They feed by stabbing their proboscis or piercing-sucking mouthparts into developing squares and feasting upon the nutrient rich contents. Once a square has been fed on, the cotton plant will usually shed the square, even if the feeding damage is comparatively light.
We recommend that field scouts use dark colored beat-sheets to quickly find and identify cotton fleahoppers. Whole plant inspections in conjunction with the use of these ‘drop-cloths’ are necessary to fully determine both the population of fleahoppers and the damage they are inflicting upon a cotton field.
The economic threshold for fleahoppers in match head stage cotton is 35% infested plants with 90% square set or worse.
This week our fleahopper counts in fields susceptible to fleahopper damage ranged from 0 to 20% infested terminals with most fields indicating 100% square retention and no fields retaining less than 98% of their squares. All fleahoppers that we found this week were adults. We will be watching fields closely for the fleahoppers and associated economic square drop.
Herbicide Resistance Info
Corn & Sorghum
For both corn and sorghum, our youngest program acres are still seed in the bag, likely being picked up by the producers this weekend and planted behind the weather destroyed acres asap. Our oldest corn came in at a V11 stage, but I have noted some area corn starting to tassel. Our oldest sorghum came in this week at V8 stage.
We still have no pests of note in either crop at this time, which includes the sugarcane aphid in sorghum. We can still find the occasional spidermite colony in corn mar-gins, but predators are starting to become a factor and making it harder to find them.
The majority of this grasshopper population has hatched and been growing and developing for several weeks now but today most are still nymphs. As the grasshoppers reach adult-hood, they will become even more mobile, just at a time of the summer we are conducting management of the habitat they like to call home first and/or the weather turns dry.
So, as that back alley or lot gets mowed, the cattle turned in native pasture, and the CRP grasses start to dry down, be on the lookout and expect to have these pests move into our more high value areas.
There are many good and labeled grasshopper products available. There are far too many crops, situations, and scenarios to go into product suggestions here, so please consult the product label for details, especially if the family pet will be in or near any area to be treated for grasshopper control.