Alabama Extension entomologist Ron Smith devoted part of the morning at the Wiregrass Cotton Expo, in Dothan, Ala., to underscore to southeast Alabama cotton producers why a little extra mindfulness with their insect management strategies can help them tighten their grips on major cotton insects.
One notable example: thrips control, which for producers of early planted cotton, caused one of the biggest headaches of the season last year, says Smith.
He says growers should be especially mindful of over-sprays on seed treatments planted from early April to May 10. This remains an important safeguard because treatments provide only about 21 days of thrips suppression, compared with the 28 days that older products such as Temik provided.
Over-sprays provided added protection during seven critical days in early season when the plants are vulnerable to thrips.
Over-sprays are most effective during the plant’s first true leaf, which is about the size of a small fingernail, Smith says. Cotton with four or more true leaves typically does not benefit from these over-sprays, he stresses.
The results of multi-state research projects reveal that acephate — either Orthene or the generic products — provide the best results. Pyrethroids were shown to be less effective.
While Bidrin was shown to be effective, Smith says this product is best held in reserve for possible stink bug infestations later in the growing season.
On the other hand, two new products, Benevia and Radiant, developed by Dupont and Dow, respectively, appear to be highly effective on thips. However, there is still some uncertainty about when they will be registered and their costs, Smith says.
Plant bugs are another species that could use more mindfulness, especially in terms of how climate patterns affect their movement, Smith says.
“You typically get really sharp spikes of plant bug movement during hot springs, although this doesn’t last very long,” he says, adding that the bug’s movement tends to be less intense during cool, wet springs, even though it lasts longer.
The most effective insecticides for plant bugs include acephate, either Orthene or the generic brands. Other options include Bidrin, although it is labeled only for the post-bloom period. Centric, while effective, also suppresses beneficial species, including fire ants.
Pyrethroids are effective, although they also adversely affect beneficial spider mites. Diamond has showed to be effective on the bugs during their post-bloom immature stage, especially when it is tank-mixed with one of the previously mentioned products.
On the other hand, single applications of Intruder, Carbine, imidaclorprid (AdmirePro), Belay and Vydate have been shown to be less effective than the others.
During July, as plant bugs linger and aphid populations build, Smith recommends using products effective against both species.
Intruder, Carbine, imadacloprid and Centric are most effective, while Diamond can be used with any of these, Smith says.
Mid-season over-sprays are especially important in cases where growers have invested in insect technology, especially now that some worm escapes have been detected.
“The over-spray is somewhat more important with Widestrike varieties, because they’re less effective on corn earworm species but, on the other hand, are more effective on armyworm species.”
He says that timing of this spray is best tailored to mid-July or early August depending on the grower’s location in the state.
Pyrethroids have proven to be an excellent fit during this period, he says.
Likewise, bifenthrin or Bidrin XPII have proven effective in cases where brown stink bugs are detected. Another option is to use the highest labeled rate of other pyrethroids.
A strange paradox within the past couple of years has been the heavy presence of armyworms in Alabama, although few have turned up in cotton.
“In both 2010 and 2011, we’ve had widespread outbreaks of what we call grass or rice strain of fall armyworms, although this strain primarily attacks pastures, hay and peanuts,” Smith says.
Fortunately for these growers, this strain is easy to control with insecticides, including pyrethroids.
The most damaging cotton pests in the South remains stink bugs. Smith does not foresee that changing anytime soon.
Eliminating the bugs may require as many as four sprays a year, at a cost of between $6 and $9 an acre.
Scouting is a critical safeguard against these bugs. The most effective way to scout for stink bugs is to examine 10- to 12-day-old bolls for signs of internal injury.
A laminated card has been developed to better ensure growers inspect the right-sized boll.
The kudzu bug, while not threatening to cotton, has emerged as a serious soybean pest and already is well entrenched in neighboring Georgia. Another species new to the region, the red-banded stink bug, is also primarily a soybean pest.
One especially serious threat is the brown marmorated stink bug, which is moving from Pennsylvania into the Appalachian region and is threatening the fruit- and apple-growing regions of the Carolinas, he says.
“Once we get it here, it may prove to be a terrible pest, especially on cotton, corn and pecans,” Smith says.