Monday, August 4, 2014

Update for the Week of August 4, 2014

The most significant insect event in the past week was the reports of plant bug tolerance to all labeled or recommended insecticides in the Tennessee Valley of North Alabama. Several of our most experienced consultants are reporting that all classes of chemistry are suppressing plant bugs but their presence and damage behind applications are still above threshold levels. This has required repeated sprays and now tank mixtures with two recommended insecticides. Under these conditions, input costs for cotton insects, particularly plant bugs, make cotton an unattractive crop option going into the 2015 season. Some areas of the mid-south have been dealing with this problem for several years. At this point, the Alabama situation appears to be confined to the Tennessee Valley area.

It has been my experience that once plant bugs get embedded in rank cotton in July, they have always been difficult to control, requiring multiple applications. So now, we have insecticide tolerance in addition to a coverage issue. Looking ahead I see a larger role for the IGR Diamond during the early bloom period in future years.

Now to a quick oversight of other insect problems on cotton and other crops; stink bugs, primarily brown, are requiring controls in some cotton fields. However, overall they are not as heavy and widespread as expected. Aphids are showing back up in some fields requiring controls. Spider mites are present in many fields. It seems like we get more calls about mite control following weeks of high temperature and dry conditions.

In soybeans we are beginning to see loopers as far north as Montgomery in older beans. So far they are only at about a third of a threshold level. Scouts are reporting an occasional corn earworm and velvetbean caterpillar in the soybean mix. The same holds true for peanuts.

Fall armyworms (grass strain) are on about every crop except cotton now. Hay, grasses, peanuts, soybeans are all experiencing the need for repeated applications for FAW. We could safely say that FAW’s have about worn out their welcome, even though they are easy to control. It seems like their preferred row crop is soybeans planted in wheat stubble. Some fields are now on their third infestation and replanting has been required due to near 100% defoliation.

In many ways, 2014 has been like “old times” to Extension entomologists with numerous phone calls about when to treat and what chemical to choose. We don’t feel like step-children to the weed resistance and disease issues this season.

Scouting crops is the first step in all insect management and control programs.

Monday, July 28, 2014

Insect Update for the Week of July 28

It has been a while since we last discussed or posted concerning the Alabama cotton and row crop insect situation. So what has been going on? No one insect has been overwhelming but treatment decisions have had to be made on a diverse array of insects and mites on all of our row crops (cotton, soybeans, peanuts and grain sorghum).

Most of the attention on cotton has been directed towards plant bugs during the past two weeks. Economic numbers of nymphs have appeared in fields that had adults in late June and early July. Where the population was detected by fieldmen, controls were applied. All recommended insecticides seemed to do a good job. One point I will make here is that some inexperienced fieldmen may have not picked up the just hatched immature plant bugs, which are very small at that stage. There seems to be a gap of time between when we stop seeing adults and when we find the small nymphs. The egg stage of plant bugs lasts from 7 to 14 days.

Aphids have been hit or miss this season. Some fields never had any aphids appear. Other fields saw a buildup sometime from mid-June to mid-July. Aphids were crashing from the fungus on July 24 while other fields were just experiencing their first aphid buildup. Where treatments were applied, insecticides were effective.

The most difficult to control pest on cotton in July was spider mites. Here is my take. We are waiting too late to find mite infestations and as a result populations are high and have been present for several weeks. Therefore, heavy damage has occurred in select fields before controls were applied. Many growers are just not tuned in to mites and are not recognizing their damage until too late. We just don’t have enough experience on when to pull the trigger on mites. I feel that weather may play a big role here. When in a period, such as early-to-mid-July, of high temp and droughty conditions we have to take a more rapid and aggressive approach to mite control.

Most of our fields are now into the 3rd or 4th week of bloom. Some fields much further along than that. This means that we are entering, or are well into, the most critical window for stink bug damage. The population has been predominantly brown up to this point. I expect the southern greens to increase the remainder of the season. Just remember that weeks 3-6 or 7 of bloom is when we need to focus on stink bug numbers and damage. For those who are just going by observations of adults, you usually have a much higher number of stink bugs than what you are visibly seeing. Crushing 10-12 day old bolls and observing for the internal injury is the most accurate way to make stink bug treatment decisions. Most fields are at the stage now that we want to use a 10% internal injury treatment threshold.

On other row crops here are pests that have occurred at damaging levels: soybeans – kudzu bugs and fall armyworms; peanuts – spider mites, lesser corn stalk borers, fall armyworms, beet armyworms and corn earworms; grain sorghum – aphids, fall armyworms and corn earworms. A new species of aphid, the green sugarcane aphid, has been reported on sorghum in both Escambia and Chilton counties. This species has done heavy damage in Texas, Louisiana and Mississippi already this season.

Moth traps in central Alabama indicate that tobacco budworm numbers are down, but bollworm numbers increased tremendously last week. A high level of budworms occurred on tobacco planted as a sentinel crop at Headland during the past two weeks.

With these comments we will close today. Remember that despite our best efforts we cannot always alert you on all pests on all crops from here in Auburn. All crops, including hay, must be scouted regularly for insect pests if they are being grown for economic returns.

Tuesday, July 8, 2014

Insect Update for the Week of July 7

A combination of adult tarnished plant bugs and clumping aphids are being reported from more fields and areas around the state each day. Overall, little rainfall has fallen in about two weeks. Therefore, crops, especially corn and cotton, are under some level of stress. Therefore, most growers are choosing to target both plant bugs and aphids with this application.

I have not had any calls on mites in the past few days but that does not mean that populations are not building in select fields. So far, abamectin at 10 oz. per acre has given good control on mites in treated fields.

Immature plant bugs are present now in the oldest cotton. I have observed several fields where a threshold of three immatures per 5 feet has been recorded on a black drop cloth. When plant bugs become imbedded in cotton in July (all stages present – eggs, immatures and adults) quite often multiple applications are needed to bring the population under control. For those that want to use the IGR Diamond, now is the time to do so. An adulticide plus Diamond, at 6-9 oz. per acre, should give control of the population for 14 plus days. It is my opinion that most of the adult plant bugs have now left wild host plants and are now in cotton. We just don’t seem to get that many moving from corn here in Alabama.

Moth traps in central Alabama captured an abundant number of both bollworm and budworm moths last week. 2014 may be the year that fieldmen, consultants, and scouts really prove their worth. There is just no way to time the appropriate chemistry at the proper time without someone monitoring insects. This looks like an above average insect year for cotton and we haven’t even reached the primary stink bug window yet. In sweeping for adult plant bugs last week, I was capturing brown stink bugs in about every set of sweeps.

Monday, June 30, 2014

How to Control Spider Mite and Plant Bug Infestations

Additional reports of economic spider mite infestations continue to come in, particularly from central and south Alabama. The heaviest infestations are already causing significant leaf shed in early square cotton. Fieldmen have reported that the lower leaves that show the greatest damage do not always have high mite numbers. Mites will continue to move up the plant to fresher leaves as the older leaves get ready to drop. Fieldmen should look a couple of nodes above the most damaged leaves in order to get a good handle on the number of mites present.

Several materials are recommended for mite control. However, some of these materials only seem to work in some locations. Examples are: bifenthrin, chlorpyriphos, dimethoate and propargite. One product in our 2014 recommendations is no longer on the market – dicofol. That leaves the newer mite chemistry as our best choice for control. These are abamectin (Agri-Mek), extoxazole (Zeal), fenpyroximate (Portal), and spiromesifen (Oberon). Abamectin is the most economical and has been the most widely selected for mite control. Ag suppliers are encouraged to have some on inventory since spider mites appear to be a growing problem.

Plant bugs continue to be reported in cotton that is squaring or approaching bloom. Plant bug immatures are now present in some of our oldest cotton. This indicates that adults deposited eggs a couple of weeks ago. Plant bug eggs are deposited into the stems of the plant in the more rapid growing areas. Therefore TPB eggs are not visible to fieldmen.

Adult plant bugs feed on tiny pin head squares in pre bloom cotton. Therefore pin head square retention is a good survey technique. Adult TPB’s can best be quantified with a sweep net. Once cotton begins to bloom, plant bugs seem to prefer feeding down in the canopy on the older squares. This results in “dirty blooms”. At this point (blooming cotton) a pin head square retention count is not the most reliable survey technique. It is also at this time that we begin to focus on the immature plant bugs instead of just the adults. The best tool for measuring immatures is the drop cloth. Therefore, in normal maturity cotton, we switch from a sweep net to a drop cloth about July 1-10 each season. Early instar nymphs are very small with long antennae and pale green in color. They move about more rapidly on a drop cloth than other insect species that may appear on the drop cloth in July.

The next few weeks should be focused on adult and immature plant bug numbers by fieldmen. While doing plant bug counts, aphids and spider mites can be observed. After July, or about the 3rd or 4th week of bloom, our primary focus should be on stink bugs. This would be true for the lower southeastern area of the cotton belt.

Monday, June 23, 2014

Cotton Insect and Pest Contols

We were cruising along last week with cotton insects kinda quiet. Thrips control was winding down on our latest planted cotton. The most prevalent observation was the white margined borrower bug, which could be found in most all fields. They were on cotton with 3 or 4 true leaves up to cotton knee high and squaring.

This week things have changed dramatically. Not to say every field has insect problems. However, in some fields, consultants are finding some level of plant bugs, spider mites, aphids and a few stink bugs. Generally, the older the cotton, the greater the chance some combination of these pests are present.

Let’s take these pests one at a time. Some have observed adult plant bugs feeding in terminals of pre-square cotton. Others report that plant bugs have dropped square retention to below 80% in cotton that will bloom within 7-10 days. A few stink bugs can already be found in these older fields. As we know from previous experience, stink bugs will attack bolls just after the dried bloom drops off if there are no larger bolls to feed on.

Added to these bug problems are the presence of aphids and spider mites. Aphids can be found clustering in the terminals of some plants in fields of older cotton. This is typically the way an economic aphid infestation usually begins. Spider mites have been treated in some fields already. Good results were obtained with Abamectin at 10 oz. per acre. Mites are still on borders of other fields and do not appear to be spreading yet.

With the combinations of pests present, it is difficult to control multiple species without a tank mix combination. My advice to growers, agrifieldmen and consultants would be to narrow your pest spectrum to the two species that offer the most near term damage potential and select a chemical or combination that will control those. It is just too early for me to consider three way tank mix combinations. At this time I believe it would be wise to target plant bugs (and stink bugs) first and I would place aphids second. These species can be controlled with a tank mix of two materials that would be rather inexpensive. A product that will give good control of plant bugs and stink bugs would be my first choice in the tank. If this product does not control aphids, I would add one that did.

This would leave the mite issue unaddressed. I just feel that we need to protect fruit first and deal with stress from spider mites in the weeks ahead.

There are a number of ways to tackle this tank mix issue for bugs and sucking pests. One would be a mix of pyrethroid and imidacloprid. There are too many to mention all at this time. I will be happy to discuss the various options by phone at 334-332-9501 if you are having problems deciding what approach to take.

Good luck and I’ll be back as we observe or hear of other information to pass along.

Updates from June 20, 2014

  • Several more reports from diverse areas of the state about adult plant bugs at damaging levels in pin head square and older cotton.
  • Plant bugs continue to increase on wild host plants on roadsides and field borders. Both dark (old) adults and immatures present in SE AL.
  • Tobacco Budworms foliage feeding on peanuts near Enterprise, AL. Newer chemistry (Belt, Blackhawk, Steward) will be necessary for control.
  • Fall armyworm (likely grass strain) feeding on peanuts in southwest AL. Pyrethroids will give excellent control.
  • Snails in abundant numbers observed on cotton from Walnut Hill, FL to Columbus, MS. No controls suggested but net sampling for plant bugs difficult.

Monday, June 9, 2014

White Margined Borrower Bugs in Alabama