Texas LRGV: Few Pests in Cotton, Midge Prevalent in Sorghum

General Situation

Fields are saturated again this week as we received some heavy rains on Tuesday, scattered showers Wednesday and then heavy rain again yesterday (Thursday). Many fields were saturated from the rains received in the weeks before and then this week Valley wide most areas received anywhere from 2-5 inches with certain areas receiving 6-7 inches causing some flooding.

We have lodging in some of the mature grain sorghum crops where there were high winds as well as waterlogged cotton in some areas with standing water in the fields. Our heat units have been very low compared to previous years as we have had almost 3 weeks now with rainy overcast conditions making it hard for fields to dry out and plants to mature.

Hopefully in the next couple of weeks we will have more sunshine for our crops to mature.

Cotton

As far as pests go in cotton not much going on for now. Still seeing just a handful of cotton fleahopper adults and nymphs in cotton fields. It is during the first 3 weeks of squaring that finding 15-25 cotton fleahoppers (nymphs and adults) per 100 terminals may cause economic damage.

Once bolls are present and the cotton begins to flower fleahoppers are Not considered a threat anymore. This is important since majority of Valley cotton is past the threat of fleahopper damage, however we do still have a few late planted cotton fields that might need to be checked for fleahoppers.

Grain Sorghum

This week it was very easy to find midge in flowering sorghum. Every field we checked that was flowering we found anywhere from 2-6 midge feeding per head.

AgFax Weed Solutions


When checking for midge inspect the heads for a small orange/reddish flying insect around the yellow flowering spikelets as this is where the female will lay her eggs, usually about 50 yellow-white eggs, the adults only live for one day. The eggs hatch in 2 to 3 days so you must check daily for sorghum midge as new populations emerge/hatch each morning.

It is imperative that if you have flowering sorghum you try to get out there in your muddy fields and check to avoid yield loss if present. As little as one midge per sorghum head is enough to warrant treatment.

We are still finding about 3-5% headworm infestation (corn earworm & fall armyworm) in many soft dough stage sorghum fields. The economic injury level for headworms in commercial sorghum is about 1 to 2 larvae per grain head.

When scouting for headworms first inspect the sorghum plants for frass on leaves and for frass on the ground between rows. Take a white bucket and beat the heads to dislodge the larvae. To get a good idea of what’s going on in your field make sure to beat at least 30 heads.

You can find insecticide treatment options for headworms on Page 37 in the Sorghum pest management guide.

We did find rice stink bugs at threshold in some sorghum fields again this week. For rice stink bugs the control threshold is generally around 1rice stinkbug per head and you would use a beat bucket as well to bang them off the sorghum heads into the bucket to get a good estimate of populations in the field. Control options are also at the link above on page 45.




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