Texas LRGV IPM: More Fleahoppers in Cotton; Sugarcane Aphids Take Off in Sorghum

General Situation

Hot and muggy this week as the LRGV received some rain on Monday and Tuesday and a little on Wednesday. Harlingen, Raymondville and Weslaco areas received anywhere from 0.5 inches to 0.7 inches but in other areas like Alamo, Pharr, and Donna they received up to 3 inches of rain. There were even some reports of sesame, tomatoes, cotton and melons in the Alamo area that received some hail damage but in isolated areas.

Cotton

Cotton continues to grow this week as we are seeing mainly the same pests as previous weeks. Did pick up on light red spidermite populations in the La Feria and Mercedes areas but nothing that warranted treatment. Starting to see a few whitefly adults here and there.

Fleahoppers continue to be the main pest of concern as all cotton is in squaring stages and older cotton is now in blooming stage. Many are spraying for fleahoppers this week. Fleahopper adults and nymphs like to feed on the squares by sucking the juices causing cotton squares to just dry up, turn brown/grey and fall off. 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.

When scouting for fleahoppers, each time you sample (weekly is good) you will want to check 25 terminals in at least 4 locations of a field starting when the first squares are appearing. If you notice anywhere from 15 to 25 fleahoppers per 100 terminals with squares being lost (rule of thumb: 10% the first week of squaring, 15% the second week of squaring, and 25% the third week of squaring, with treatment rarely needed after first bloom) treatment is justified.

Bollworms. In parts of Texas we have found evidence of bollworm resistant to one or more Bt genes in our Bt cotton. Fortunately for South Texas we have not seen or experienced increased bollworm pressure like in other areas of Texas. However, if you have a Bt cotton field that has bollworm pressure this year I would like you to please contact me, (Danielle Sekula, 956-968-5581) so we may go out and inspect and collect the larvae if need be. We would like to be ahead of any resistance issues and are asking for your cooperation in protecting our cotton crop.

Grain Sorghum

Sugarcane aphid populations have increased drastically from last week to this week given the increase in moisture and humidity paired with the high heat we received this week. Saw many alates this week (winged sugarcane aphids) migrating into sorghum fields. I saw very high sugarcane aphid populations in fields that have sorghum varieties that are high yielding but have no tolerance or resistance to sugarcane aphids.

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So… if you know you planted a variety that has no sugarcane aphid tolerance/resistance I suggest you go out and scout it because it might have high sugarcane aphid populations that are too overwhelming for the predators to keep up with. Other varieties with sugarcane resistance/tolerance have moderate sugarcane aphid populations and remember if you are averaging 50 sugarcane aphids or more per leaf after checking four areas of your field looking at about 40 leaves then treatment is justified.

We were also out looking for midge this week and was pretty amazed that I have not seen any yet in flowering sorghum though I heard a report that some was seen in the Santa Rosa area in flowering sorghum. Seeing a few more rice stinkbugs as well this week in sorghum.

Corn, Sesame, and Sunflowers

Noticed some leafminer damage in a couple of corn fields this week on the leaves. Also saw some bacterial blight but in isolated areas and with the high heat there is no cause for concern. Noticing some tarnished plantbugs as well as a few stinkbugs in the sesame and will see in next few weeks if they will raise cause for concern.

I have not picked up on any mirids just yet, but I suspect we will start to see some as I am noticing more whiteflies in the foliage and mirids like to feed on whiteflies (remember that mirids like to feed on sesame and can stunt its growth but if whiteflies are present they will feed on them first and might not pose a threat all season if there are sufficient food sources of them). Sunflowers heads are maturing fast as seeds are drying up as we gear up for harvest.

Be on the LOOK out for:

We are noticing high false chinch bug populations in mature canola and carinata that are migrating out of those fields as they look for new food sources. Please beware if you have nearby crops for false chinch bugs have sucking piercing mouth parts that help them feed on plant juices. False chinch bugs are known to congregate on sorghum heads and feed on the seed as it matures.

They have also been known to populate young cotton and can overwhelm seedling cotton up to 6 true leaves. I had also received reports two weeks ago of false chinch bugs destroying a nearby onion field before harvest. So please be on the look out for these critters as they can be very destructive in overwhelming numbers and it looks like they might pose a threat as canola and carinata is being harvested and they will begin to migrate to nearby fields.

Also in the McCook area I noticed quite a few whiteflies in the foliage of the sunflower fields. My concern is sunflowers will be harvested soon and where will all the whiteflies go? My prediction is they will go to nearby cotton and sesame fields. My concern is for the nearby cotton. So be mindful of this as well as we continue to scout next week.


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