The past two weeks saw record rainfall for August in SOME parts of the state, however the drought persist in others. Hopefully the falls rains will be more generous and the whole state will recover.
The Bollworm complex is becoming more present throughout the state. The general scenario is to find live worms but no damage squares OR find damage squares and no live worms. This indicates that the technology is working where there are live worms, and damaged squares means the technology is overwhelmed.
The economic threshold is 6% damaged squares with live worms present in Bt cotton. The crop stage is critical to warrant a control spray. Cotton that is at cutout or past cutout means the likelihood of economic loss is very low. Please call this office if in doubt if a control spray is needed.
STINGBUGS, APHIDS, SPIDER MITE
Stinkbug control sprays continue especially along the counties along the I- 40 corridor. We need to once again caution about using pyrethroids even with a combination of aphicide to control stinkbugs. This is not because they will not do the job but it is due to the likely aphid infestation that can later occur.
Pyrethroids are just too harsh on beneficial arthropods to be viable. It is not the aphids in the field at the time of application one has to worry about – it is the subsequent aphids that move into the field to recolonize it.
Adult aphids are always on the move. Aphid reports were on the increase but due to the recent rainfall the population in most areas have decreased. The population in some fields however have rebounded more rapidly and control measure had to be used.
Spider mite infestation have also been deceased with the rain. The general feeling is that beneficial arthropods are slow to develop this year especially the Lacewing population. Hopefully this will turn around and aphid population will further decrease.
Cotton aphids are small, soft-bodied insects commonly referred to as “plant lice”. Aphids occasionally occur on cotton in such high numbers that control measures should be implemented.
Build ups are localized and usually occur after the use of insecticides that are harsh on beneficial arthropods, including pyrethroid types. The insects are found on the underside of leaves and along the terminal stem, causing misshapen leaves with a downward curl and stunted plants.
Aphid damage cotton directly by sucking juices from the plant and indirectly by secreting honeydew. The honeydew is sticky and can lower the grade of lint. Sticky cotton may result in significant problems during the spinning process at mills. A sooty mold can develop on the aphid honeydew and discolor the lint.
For more information on aphids, click here for the Texas A&M Aphid Management Guide. One chemical not mentioned in the guide is SivantoTM from Bayer CropScience. It is also labeled for control of cotton aphids. The product rate of 7 to 14 fluid ounces per acre is noted on the label. Due to the high probability of beneficial arthropod control of cotton aphids, if this pest is found, any potential control
measures should be carefully considered. If you have any questions concerning aphid populations, call this office. For sticky cotton sources and solutions, click here for the University of Arizona Sticky Cotton Sources & Solutions guide.