Tuesday, July 27, 2010

Statewide Cotton Insect situation

We have reached the point in the season that it is difficult to generalize about the cotton insect situation statewide. Some fields have been sprayed while some have not. Some of those sprayed have received a pyrethroid while others have received a phosphate such as Bidrin for bugs only. Scouts are reporting that behind pyrethroid sprays they are finding escape worms in some fields and escape bugs (both plant bugs and brown stink bugs) in others. More escape worms are being reported in DP555 (sirge gene) then the Bollgard II varieties. As each day passes more field people are reporting Fall armyworms in blooms. It is suspected that the extreme heat has reduced the effectiveness of the pyrethroid chemistry. This happened in the early 1980's, with the earlier generation pyrethroids, when the temperatures approached 100° F.

My suggestion would be to target the insect that is potentially the most damaging. If the problem is escape bollworms I would continue to select a pyrethroid. Use a high labeled rate, add some crop oil to the spray mix, and add a phosphate if high levels of bugs are present. If the problem is primarily bugs, then just go with a phosphate such as Bidrin at 1 gallon to 21-24 acres. If Fall armyworms are in the mix the pyrethroids will not give acceptable suppression. Under this condition, I would go with Diamond (9 oz) Steward (11 oz), Belt (3 oz) or Tracer (2.5 oz).

Soybeans- A few green cloverworms and soybean loofers can be found in many fields at non damaging levels. The greatest insect threat statewide is likely stink bugs. The stink bug population has been primarily brown's up to this point. However, yesterday at the Gulf Coast Research Station, the southern green stink bugs were out numbering the browns. Also, at this site the recently discovered red banded stink bug was present and had done heavy damage to beans at the R-5/6 pod filling stage.

Friday, July 23, 2010

Stink bugs and plant bugs

Cotton- A heavy bollworm moth flight has been ongoing this week (July 19-23) in the Florida Panhandle and areas of south Alabama. Small larvae have been observed in white blooms as far north as Montgomery. Many of the eggs are being deposited on large squares and three days later the small larvae are moving immediately into white blooms.

A low number of Fall armyworms are now being reported in cotton in central and south Alabama.

Both stink bugs and plant bugs (both adults and immature) (tarnished and clouded) are in most of all central and south Alabama fields that have not been sprayed since the first of July. A good clean-up spray is needed in most fields and probably should have been made 7-10 days ago.

The drought and heat has taken its toll on cotton that escaped scattered thunderstorms.

Friday, July 16, 2010

Red Banded Stink Bug in Alabama Feeding on Soybeans

Another significant insect event this week was the discovery of the red banded stink bug (Piezodorus sp.) feeding on soybeans in Baldwin County. This species had previously been reported from most other southern states, except Alabama. They have been reported to be very damaging to soybeans in Louisiana and other mid-south states. This species has the ability to be more damaging to beans than the other more common stink bugs (brown and Southern green). Most reports indicate the red banded may be more difficult to control with insecticides. All entomologists agree that populations can rebound greatly within 7-12 days after a spray.

Stink bugs, tarnished plant bugs and "worms" in cotton

My cotton insect observations this week were as follows: many fields have a number of immature (late instar, soon to be adult) tarnished plant bugs. This stage of immature, along with the adult stage, is what will be giving us our “dirty” blooms in the days ahead. Mixed in with these immature TPBs are a few fleahoppers (both immature and adults) and a few immature clouded plant bugs. Many fields would profit from a plant bug complex “clean-up” spray if it has not already been done during the past two weeks.

Aphids have built rapidly during the past week in a number of fields. Where cotton is currently under drought stress, the presence of aphids and honeydew on all plants might influence the choice of chemistry for this bug clean-up spray.

Several fields of April planted cotton in southeast Alabama had treatable levels of “worms” this week. These worms were likely already about a week old on July 15, which means the eggs were deposited around July 5. This was during the period when most moths observed were tobacco budworms. Appropriate chemistry would be needed if targeting these worms. By next week (July 19-26) the eggs deposited will likely be bollworms and pyrethroids would be the most economical chemistry.

Even though the percent internal boll damage may not have increased in recent days, the brown stink bug problem has not gone away. My thought as to why the percent damage hasn’t gone up is due the fact that peak boll production is close in cotton planted in late April. Let me explain. A week or two ago we had about one boll per row foot about 10-12 days old (the size stink bugs prefer). Some of our stink bug damage levels at that time were running 20% or more. At one per foot this would be about 14000 bolls per acre x 20% or 2800 per acre with internal damage. At present these same fields have up to 3 or more 10-12 day old bolls per row foot. This would mean that 42000 bolls per acre are at risk, but the stink bug population hasn’t increased greatly at this point. The percent internal stink bug damaged bolls has gone down in many fields but that doesn’t mean we are not taking economic damage. Ten percent damage to 42000 bolls per acre is 4200 bolls. Percentages can be misleading. The damage we are incurring is a function of two things – the number of bugs present and the number of bolls at risk. In the old days this situation existed with the number of squares and the number of boll weevils. The damage percent would go down prior to increasing rapidly.

Not only will we wake up one day a couple of weeks down the road with more internal stink bug damage than we thought, but also with a sharp increase in the percent damage. This will be a function of more stink bugs present by then, but also a reduction in the number of bolls per acre that are in the desired feeding size. Borrowing a line from one of our recent politicians “this makes sense to me – does it to you”?

Redbanded stink bugs

On Tuesday, I surveyed some soybeans at our Gulf Coast Research Station at Fairhope, and I’m 99% sure that I found red banded stink bugs there. These beans were at about 30% podfill. I was finding about 1 adult and 2 immatures per 6 row feet. If it is the red banded, that’s the first time the insect has been found in Alabama. It’s probably been in south Alabama, but maybe we just haven’t been looking for it enough.

Tuesday, July 13, 2010

Aphids and bug complex building, fall armyworms in second generation in pastures, fleahoppers appear

We’re getting more reports of aphids building in cotton. They’ve been slow to increase but still have reached treatable levels in some fields. While we were doing our beat sheets last week, I noticed in some of the older cotton that immature brown stink bugs were turning up where we had adult brown stink bugs earlier. So, they’ve been in there long enough now to turn over a generation. Most of the plant bug population right now are in immature forms coming off of the June adults. Fields that were sprayed for bugs appear to be pretty clean, but others have populations now that are at or will shortly be at damaging levels, so we’re really close to making applications to clean up the bug complex on everything.

We’re still not seeing signs of the huge tobacco budworm flight that was underway in southwest Georgia 2 weeks ago. It’s amazing how fast budworm activity drops off as you travel 2 counties west into Alabama. We have a long history of similar patterns – heavy pressure in south Georgia but hardly anything in southeast Alabama. We’re into the second generation of fall armyworms, the grass strain, in coastal Bermuda and other hay fields in southeast Alabama.

The garden fleahopper has been causing damage in a 25-acre cotton field in Mobile County. This is the first time I’ve seen the pest in cotton in the 39 years I’ve been working the crop and didn’t know for sure what the insect was when a consultant emailed me samples of the pest and damage. But Mississippi State University recently released an excellent color insect guide for cotton, and the garden fleahopper was included in it, which allowed me to ID the insect. Evidently, it’s been enough of a pest at some point in Mississippi cotton that it made the book.

I have a feeling we’ll see a lot of brown stink bugs in soybeans when they start setting pods. They’re certainly nearby, although probably not in soybeans to any degree yet. Stink bugs are smart enough that they won’t hang around too long in a crop that doesn’t provide a food source. Typically, they’ll leave corn within a week of when it starts drying down and, as if on cue, they’ll shift into soybeans when they start setting pods. We’re following a population of them right now at our Gulf Coast research station.

Wednesday, July 7, 2010

Insect Complex Developing

Several fields were surveyed yesterday (7/6/2010) in central Alabama. My findings were as follows: aphids continue to be low to non-detectable in many fields; drop cloth samples yielded early instar immature plant bugs, and an occasional fleahopper, frequent adult clouded plant bugs, and adult brown stink bugs. All of these were at non-treatable levels at the present. However, as each day and each week passes the bug complex will become more abundant and damaging to the point that the entire complex will require controls. I would key on damage to the thumb sized bolls (until quarter diameter bolls are present) for stink bug decision and to a combination of dirty blooms and the number of immature plant bugs per row foot for that species.

I would advise field surveyors to begin switching from a sweep net to the drop cloth as cotton begins to bloom. The majority of the plant bug population for the next couple of weeks will be immatures that have hatched from eggs deposited by migrating adults during the month of June.

The large tobacco budworm flight has not reached southeast Alabama yet. I will be in southeastern Alabama tomorrow and will observe for moths, eggs, and small larvae at that time.

Calls received this week have centered on what to use for a complex of aphids, plant bugs and brown stink bugs. No one chemical would be the top choice for this complex. A pre-mix or a tank mix of two chemical classes would likely give the most effective control of this complex.

Thursday, July 1, 2010

Tobacco Budworm Moth Flight

Another significant insect event is now occurring in extreme southwestern Georgia. Consultants yesterday were reporting a very heavy tobacco budworm moth flight with eggs on most every plant. This event means nothing to growers who have planted Bollgard or WideStrike varieties. However, to those with fields planted to conventional varieties, it is a different predicament. On the one hand they have adult stink bugs and hatching immature plant bugs, while on the other they need beneficials to be present during this upcoming budworm flight. This budworm moth activity will likely extend across southern counties of Alabama during the next 10 days, and may even reach the central Alabama area. Tobacco plants, grown as a sentinel crop in Prattville, AL had budworms from the previous generation of budworms. The budworm egg lay on tobacco at Headland, (southeast Alabama) continued from Memorial Day in May until about June 20. It will be difficult to advise growers with conventional cotton during the first weeks of July. They just need to realize that most worms will be budworm species and pyrethroids will not give worm control during this window of the season.

Brown Stink Bugs

Adult brown stink bugs continue to be observed in many fields. They have been present for about a month but could not do much damage until about the second week of bloom when small thumb sized bolls were present. I observed fields of late April planted cotton in southeastern Alabama (2-3 weeks of bloom) yesterday that had up to 40% boll damage from brown stink bugs. When stink bugs are present prior to bloom, bolls smaller than quarter diameter should be sampled as soon as they are available.

Plant Bugs

A few fields have received controls for adult tarnished plant bugs during the past week. However, it appears that most of the June migratory adults have died off and we should shift our focus to their immature offspring in the next 2 to 3 weeks. Unlike the Mid-South, our movement of plant bugs comes primarily from wild host plants around field borders during a one to three week period in June. Thereafter, we only have to control their offspring within fields. This period can extend for several weeks since the June migratory adults deposited eggs over a multi week period. Surveyors should now shift from the sweep net to a drop cloth as they focus on the July immature population in blooming cotton.