I’ve had several calls or comments about corn leaf aphids in corn (pictured below). This is the most common aphid found in corn, but treatment is rarely needed. A number of people have noticed that many aphids appear to be dead or dying. This is not surprising given that all field corn seed is treated with Cruiser (thiamethoxam) or Poncho (clothianidin), both of which are systemic insecticides that have activity on aphids. Treatment for corn leaf aphids would only be recommended in cases were there were obvious effects on the plant including wilting or dying leaves. This rarely happens and would typically require dozens, maybe hundreds of aphids on a seedling.
Although aphids will migrate into fields, it is likely that some are coming from weedy grasses that were in the field at the time of emergence. The weather is a contributing factor because it delayed timely burndown applications. These same fields may be at risk to cutworms infestations for the same reason, so be alert for this pest. A pyrethroid insecticide at standard use rates would be the standard treatment for either pest.
Corn leaf aphid (courtesy of Iowa State University)
Off the wall question:
I read this morning where there have been some trials in the midwest with corn & soybean to see if there are any benefits gained by the foliar application of sugar. One of the few differences between treatment and check was that the availability of extra sugar as a source of food for beneficial insects increased their population in the treated crops.
Is there a beneficial insect that if allowed to thrive and multiply could help cotton farmers manage tarnished plant bugs? The repeated spraying for TPB wears us out, creates stress, & makes us question our sanity. If a creative IPM program could be designed & implemented that would decrease these endless sprays, the attractiveness of cotton production could be re-kindled and growers would have an option to the grains.
I am willing to try a creative/imaginative approach to TPB control, if you are willing to invest time in research and management options. Let me know. RMJ
Richard,
I hold very little hope that spraying sugar will have any substantial effect on beneficial insect populations in cotton, especially those that could help with plant bugs. First, plant bugs seem to thrive in low spray environments where beneficial insects are often plentiful. There are several predators and a parasite or two that feed on plant bugs, but they just don’t appear to have the ability to effectively reduce populations below economically damaging levels. This is especially true of the parasitic wasps. There are just not any that do much good, and it is these natural enemies that would more likely benefit from a sugar source. Even if you could have some impact, it would probably not be enough to prevent insecticide applications that would disrupt your efforts. Second, plant bugs are mostly a migratory problem early season, and the mobile adults often get to the crop before the predators (and are are harder catch). Most of the serious problems occur mid-season when battling a lot of immature life stages that are easier targets for predators. But this is the time the plant is producing a lot of its own sugar (nectar) already. This certainly helps increase population of natural enemies. I’ve never tried the math, but I bet the plant is producing way more sugar during bloom than could be economically sprayed. By the way, sugar is an attractant to moths, so there could be some bad with any good from spraying sugar.
There are currently no silver bullets for managing plant bugs. It takes a system approach of managing earliness, sampling and threshold based sprays, choosing good insecticides, etc. A substantial part of my efforts are dedicated to BMPs for plant bugs. There are some transgenic technologies under development that may help simplify management for plant bugs (at a cost I’m sure) but these are not likely in the next 5 years. We’ve looked at approaches including area wide management of alternate weed hosts and use of trap crops, but implementation is a challenge on an area wide basis and considering the relatively small field sizes in TN. I’m open to suggestions. There are a lot of people trying to figure this problem out. Of course part of this is just economics changing perceptions. $3.00 corn and $6.00 beans would make the hassle of growing cotton a lot less aggravating. We really are spraying less than we did when boll weevil was around and making better yields.