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Friday, September 6, 2013

Moth and Worm Invasion


               Local insect populations have built, or possibly rebounded, over the summer months.  The season’s rains, while not drought busting, have provided lush habitats for several species.  As a result, we are feeling inundated with multiple, sometimes overlooked, species of insects.  The most notable belong to the Lepidoptera order.  In Hale and Swisher Counties we are already dealing with economic populations of FAW (fall army worms) and bollworms in sorghum and some cotton, but these are far from our only species of interest, or the only ones that could pose problems. 

                Over the past few weeks, other area and regional entomologist and I have noted and fielded several questions about high numbers of ‘odd’ caterpillar larva and moths of various species causing a stir.  The White-lined sphinx moth was the focus of Dr. Ed Bynum’s (Texas A & M AgriLife Extension Entomologist - district 1) August 30th edition of the Panhandle Pest Update.  In July, Manda Anderson (EA – IPM, Gaines County) mentioned garden webworms in her weekly newsletter.  This week Dr. Pat Porter (Texas A & M AgriLife Extension Entomologist – District 2) sent out alerts regarding the yellow stripped armyworm (true armyworm).  All district IPM agents responded to Dr. Porter’s alert stating that they too were finding the yellow stripped armyworms at varying levels alongside several other foliage feeding larvae. 

                After noting intense feeding upon pigweed by an unknown Lepidopteron species in the area, I enlisted the aid of Dr. Bynum and subsequently Dr. Porter in identification.  This species turned out to likely be the garden webworms that Manda had mentioned back in July spreading, in very high numbers, across the region.  These garden webworms can currently be found locally by the thousands feasting upon Palmer, kochia, and even some Johnson grass, doing what our best efforts in weed control could not (unfortunately they are doing it after the weeds have seeded out).  However, the garden webworms are not working alone.  There is a healthy mix of yellow stripped armyworms, beet armyworms, various cutworms, multiple looper species alongside the webworms, and likely several others such as the smartweed borer. 

                So far, this conglomeration of foliage feeding caterpillars has focused on weed species and just a few field margins.  Several of these species are known crop pests.  It is possible, maybe even likely, that once the weeds have been laid to waste, these hungry caterpillars could move to our area crops, gardens, and yards.  As veracious as these caterpillars are, they could devour and ruin a small garden, hedge, or certain trees in a matter of hours and a crop field in days.  On the crop side; any BGII cotton should be safe as should any Bt corn.  All sorghum and other non-Bt crops are at risk. 

I suggest keeping an eye on these caterpillars.  In the meantime, we are getting to see much of our weeds turn brown.  Hopefully, that is all they will attack.

 

Please call or come by if I can help,

Blayne

               

Thursday, September 5, 2013

Fall Army Worm Concerns in Sorghum (& corn)


           We have been expecting some pest troubles to develop in our later crops in Hale & Swisher counties for some time.  Last week we found several sorghum fields (most just entering soft dough stage) with economic bollworms, one of the species that commonly make up the sorghum headworm complex.  Unfortunately, we are finding that the bollworms are not alone. 

            This week we are finding several FAW (fall army worms) following the bollworms into the sorghum fields, just a touch behind.  The ET (economic threshold) for any sorghum headworm is roughly the same without much regard to larva species.  Literature regarding headworm control, etc. can be found in Managing Insect and Mite Pests of Texas Sorghum.  However, species identification is crucial if your field does have an economic headworm problem.  Most of the labeled products for bollworm (i.e. corn earworm) will not control FAW larva.  In this case, we must change our recommended treatment to a product that has a chance to control both.  Changing products does come with a higher sticker price, so we really need to make certain of your species present before applying any labeled product for headworms.  Good photos to aid with larva identification between bollworm and FAW can be found in the July 5 edition of FOCUS.

            Of course sorghum is not the only area crop the FAW will attack.  Corn, cotton, early planted wheat, and even several hay crops are at risk.  I am finding several FAW in late planted corn, and a small number in cotton, but at this time they seem to prefer the later planted sorghum that is just moving toward soft dough stage. 

 

Please call with any questions,

Blayne