Texas LRGV Crops: Cotton Blooming, Tarnished Plant Bugs on the Move

It’s been very hot this week across the LRGV. Tuesday and Wednesday the coast received varied rain showers. But, overall, we are very dry and many growers continue to irrigate. The dryland crops are still stressed from lack of rain.

Cotton

Cotton is in full bloom and seeing some good boll set in most areas. I noticed some cotton shedding its squares after this irrigation.

Tarnished Plant Bugs, Verde Bugs

I have received reports of treatments going out for tarnished plant bugs that are feeding on immature bolls along the river. Threshold for tarnished plant bugs is 10 tarnished plant bugs/100 sweeps. We were sweep netting in the La Sara, Lyford areas and picking up on zero plant bugs per 100 sweeps but as we moved to the Sebastian and Santa Rosa areas we were getting about 3 per 100 sweeps. Still not at threshold but they are starting to move into cotton fields with immature bolls.

Sorghum had been sprayed with glyphosate in these areas to get ready for harvest so I suspect the plant bugs are migrating out of the sorghum and sesame fields. Adult tarnished plant bugs are winged and brown in color mottled with red, yellow and black.

Plant bug nymphs are similar to the adults, but they lack wings and are greenish in color with black spots. Females lay whitish eggs inserted into the host plant and hatch in about 8 days. From egg to adult the tarnished plant bug life cycle is about 3 to 4 weeks and produce 5 generations a year.

I saw some Verde bugs in the Bayview and Los Fresnos areas this week. Verde bugs along with tarnished plant bugs pierce immature bolls and squares with their mouth parts causing boll malformation to complete fruit loss. Verde plant bug adults are about 1⁄4 inch long in size and are light green in color with long antennae and red eyes. 

Whiteflies

Cotton fields along the river were sprayed this week for whiteflies. Many adults and immatures have been present. Any cotton growers located near sesame along the river need to be proactive in controlling whiteflies as they will overcrowd on the underside of sesame leaves and then migrate to nearby cotton fields and to continue feeding.

Sorghum

Treatments went out this week for midge in flowering sorghum fields.

There was heavy headworm pressure in soft dough sorghum along the coast in the Bayview, Los fresnos and Progreso areas.

Many ricestink bugs present in softdough sorghum but most were being controlled along with midge or headworm applications. Sugarcane aphid pressure across the Valley has calmed down as we gear up for harvest. I predict a second peak or rise in sugarcane aphid populations will come the end of June so late sorghum and even sorghum prior to harvest should be scouted to avoid a sticky situation —  literally.

Sesame

We found mirids (Nesidiocoris tenuis) this week in sesame across the Valley. Most fields do not have abundant mirid populations yet but will need to keep a close eye in case things change especially with this high heat.

While no threshold has been established for N.tenuis we did notice back in July of 2015 that it took as little as 3 to 5 mirids per sesame terminal/plant to cause significant damage. Right now I have only seen that situation in a handful of fields and there were many whiteflies present for them to feed on.

The majority of the Valley has mirids present at an average of 1 per plant and the sesame plants look very healthy. Mirids are a type of plantbug that suck plant juices and can cause necrotic damage and stunting of growth to the sesame plant as well as injury to the pods.

N. tenuis mirids adults and nymphs are lime green in color measuring no more than 5mm in size. They are fairly small and the adult wings, when closed, make a heart shape. Damage looks like a reddish/brown scaring to the plant tissue along the stem, leaves and on the seed pods.

Mirids N. tenuis also can be predators to whiteflies feeding on both adults and immatures in the lower canopies of the sesame when present. However, mirids can develop successfully on the sesame plant alone and will feed on the plant more when they have depleted their food source (in this case whiteflies) or there is an abundance in mirid populations.

Signs of high mirid pressure feeding on the plants will be yellowing on the leaves and brownish necrotic damage and the leaves curl under. Monitor for mirids and treat if necessary since their feeding can hurt yield potential. Products labeled on sesame that control mirids are Transform and Mustang Maxx.

MARK YOUR CALENDAR!

Fike Farms Field Day in Edinburg, Texas, will be on Tuesday, June 11 starting about 2 p.m. with a tour of corn and sorghum hybrids. Dinner will follow. Questions: Call Vidal Saenz, County Extension Agent-Agriculture (Hidalgo County) – (956) 383-1026

 

 


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