Update for the week of July 22nd

The past 7-10 days has been about as quiet insect wise as I ever remember for that time of the season.

Insect wise, we still have a few scattered Tarnished Plant Bug adults and a few immatures in some unsprayed fields – but I am not aware of a single field that has economic or treatable levels. In many instances where I have actually monitored fields, I found that part of the plant bug population is the clouded plant bug species. This species has been present in some fields in Alabama for most of the month of July.

Spider mites are still hanging around but have not exploded in recent weeks. The weather in the form of multiple thunderstorms appears to have slowed mites. Speaking of weather, some areas of the state have received multiple rain events of one to two inches or more while others have received only tenths a few times. Cotton ranges from as good as it has ever looked to knee high and blooming out the top depending on the planting date and the amount of rainfall received. In general, the earlier planted cotton that was stressed due to the heat and drought in May and June offers the least yield potential.

Back to insects now – a few stink bugs, mostly brown, are present in most fields. However, the numbers do not reflect the level we anticipated following a mild winter and the number seen on wheat at harvest time. It appears that the hot dry weather last month took its toll on stink bugs also. Boll damage to stink bugs is less than 10% in many fields. Cotton maturity ranges from the third week of bloom on late planted cotton to probably the sixth or seventh week of bloom on earlier planted fields.

Since we are at least at the third week of bloom, growers might want to consider a clean of spray for subthreshold levels of plant bugs and sink bugs in fields that have not received a foliar insecticide application yet in 2012.

This used to be the time we could also catch some escaped bollworms with this clean up spray. However, at this point, the bollworm flight statewide is very low and escaped worms are almost non detectable. Still the bug complex alone could help justify a clean up spray.

This is the way we see it on July 24, we will be back with an update as the season unfolds and conditions change.

Insect and Weather Update for the week of July 9th 2012

The past 10 days have been characterized by heat, drought, scattered thunderstorms, aphids, and in some cases spider mite decisions. Some areas have received one or more rainfall events of 1 to 3 inches or more while others are still suffering extreme drought. Some of these storms have brought high winds, downed trees, demolished buildings and hail.

Insects have been rather quiet overall. Many field men have made aphid treatment decisions with significant acres treated. In at least one incidence, both aphids and mites were at treatment levels. Other more sporadic fields have needed adult tarnished plant bug controls. In the majority of cases the plant bug population has now shifted to immatures. In these cases field men need to switch from sweep nets to drop cloths to quantify these immature plant bugs. Two or three immatures per drop could be considered a threshold level requiring treatments, especially if “dirty” blooms are present. Pinhead square retention is no longer the best way to look for plant bug damage since they spend more time down in the canopy feeding on larger squares (which later become dirty blooms).

I have not had any calls yet, but field men in the southern areas of the state need to pay attention to stink bugs since our oldest fields are now at week three, four or more of bloom. Weeks three through six of bloom is when stink bugs are most damaging. A good threshold for treatment during this period is 10-15% internal damage to quarter diameter (still soft) 10-12 day old bolls. Look for brown areas near the seed  and warts on the inside boll wall where stink bugs have penetrated in search of a protection source in the form of developing seed. If the population of stink bugs is primarily the southern green species then we have choices of both pyrethroid and phosphates. However, as most likely the case, the population may be predominately brown stink bugs. Here we would need a phosphate such as Bidrin or either a high rate of bifenthrin and get decent suppression.

Reports were just received of an increase of small larvae on peanuts in south-central Alabama. My guess would be that they are tobacco budworms. By July 15, newly hatched larvae will more likely be corn earworms.

Weather Conditions and Pest Control

First we will give an overview of weather conditions, especially since this may be impacting some of our insect and pest control decisions in the coming days. After a good moisture and rainfall pattern of about 10-14 days ago, our crops have reached a hot-drought stressed condition at present. The situation is worse in the northern area of the state where less rainfall fell during the last thunderstorm period. I saw corn wilted bad in the Tennessee Valley on Tuesday (June 19).

This droughty situation could well impact spray decisions with pests such as aphids and s. mites in the immediate days ahead. Aphids are building state wide and drought stress plants are where I am more suggestive for chemical controls instead of waiting for the natural fungus.

Tarnished Plant Bug adults are also being reported from some fields from the Tennessee line in the north to the Florida line in the south. Square retention is dropping, especially in fields in South Alabama that are a couple of weeks into bloom – these would be early-mid April planted cotton. Also in these some fields, adult brown stink bugs are being reported. We know from past years what stink bugs do to small thumb sized bolls when no larger ones are present.

If present in cotton, stink bugs will feed on small bolls to develop. Knowing this impacts the chemical that we may want to choose for TPB control. It needs to be a product that also controls or highly suppresses Brown Stink Bugs. The best options here would be Bidrin or a high rate of bifenthrin. Aphids in the picture would further complicate the chemical selected. Of the neonic type products, Centric might be the best choice for Tarnished Plant Bug adults, Brown Stink Bugs and aphids.

Three-Cornered Alfalfa Hopper damage is still evident in cotton, in reddish stunted plants that have a girdled and swollen area around the main stem. However, this damage is old now and most plants are too tough for main stem girdling by the Three-Cornered Alfalfa Hopper.

The biggest insect news of the week in Alabama was the finding of the Kudzu bug in soybeans in Cherokee County, Alabama on June 21. The Kudzu bug had been found in about 25 counties on Kudzu but this was the first find on soybeans. Alabama growers will want to lean heavily on recent research conducted in Georgia, South Carolina, and North Carolina on this new envasive pest. We need to beef up our scouting on soybeans for this pest – especially the immature stage.

Overview of 2011 Cotton Insect Season

Early Season Pests
Thrips were extremely heavy from about April 15 to May 20. A major contributor to this heavy migration of thrips from wild hosts and wheat into cotton was the extreme drought conditions and absence of rainfall events during this period.

Plant Bugs
One peak movement of adult TPB into cotton occurred between June 20 and July 1. The majority of this infestation only happened in the earlier planted fields (most mature cotton). One insecticide application was targeted to these adult TPB’s when they were detected. Few immatures were detected in these fields in the coming weeks, so no in-field generation occurred. This may have been influenced by the extreme temperatures that occurred during this period (98-102⁰F).

Bollworm
Subeconomic numbers of bollworms occurred over an extended period from about July 15 to August 10. Few fields ever reached treatment threshold. 2011 was like the lowest bollworm pressure year on record. End-of-season damage boll counts on untreated genetic cotton were less than one boll per 10 feet.

Tobacco Budworm
Budworm numbers were non-detectable to extremely light all season long. Budworm larvae were too low to detect on conventional cotton and even on attractive crops such as tobacco when used as a sentinel crop.

Aphids
Aphid numbers were very slow to build in 2011 but also slow to crash due to naturally occurring diseases. The fungal disease was slow to develop which left aphids in the system much later than normal. Aphids normally peak and crash prior to, or at, the early boll set stage but this did not happen in 2011. Also, observations indicated a resurgence of aphids in the mid canopy area of the plants in late season as opposed to the terminal area.

Stink Bugs
Stink bugs in 2011 were fewest in number and damage of any year since the boll weevil was eradicated. This was likely due to the colder than normal winter temperature effect on the southern green species and the extreme spring heat and drought effect on the brown species. The majority of the few stink bugs observed in 2011 was the brown species.

Fall Armyworms
The “rice or grass” strain of the fall armyworm was abundant over much of the season in pastures, hay, and grasses. This strain will feed on peanuts but not on corn or cotton. They are easy to control on pastures with pyrethroids and numerous other labeled agricultural insecticides.

Cotton Insect Management 2011

Points for Discussion:
1. Low Input System - Conventional vs. Technology
2. Evolution of Bt Cotton - Various Genes Involved
How do they compare and what is in the future?
3. Phase Out of Temik
What will be the greatest impact?
4. Stink Bug Research Towards a More Rapid Survey Technique
Factors that influence external vs. internal stink bug boll damage.

5. New Damaging Insects
A. Plataspid (Kudzu) Bug

B. Brown Marmorated Stink Bug

C. Redbanded Stink Bug


A. Plataspid (Kudzu) Bug

 Native to Asia

First detected near Athens Georgia in the fall of 2009

Has since spread over much of Georgia, South Carolina and into a few counties in North Carolina and Alabama

Feeds primarily on legumes

Reduced soybean yields by about 20% in 2010 test fields in Georgia

Feeds on stems and leaves

Has high reproductive potential

Can be controlled with pyrethroids and other chemistry

Is a public nuisance problem in fall of the year as they enter homes and buildings to hibernate.

B. Brown Marmorated Stink Bug

First discovered in Pennsylvania in late 1990s

Native of Asia

Big problem in specialty crops in mid-Atlantic states (grapes, apples)

Caused 60-90% loss in peaches and apples in 2010

Called Interstate Bug since it spreads by trucks and campers

Has wide host range - feeds on about everything

Have been found in three Alabama counties in late 2010

Has long proboscis so can go through the husk of corn

Pecans may be huge host in the southeast

Causes more damage per bug on soybeans than green or brown stink bug species

Expect to be economic pest of cotton

Will likely have heavy field edge or border damage
Invades homes for hibernation sites in the Fall

3. Redbanded Stink Bug

Native to South America (Brazil)

First found in Louisiana in 2000

Observed on soybeans in Baldwin County, Alabama in July 2010

Is sensitive to winter temperatures below 20 degrees F

Has high reproductive potential

Is primarily a legume feeder

Can cause heavy damage to soybeans

Feeds earlier and more aggressively than other stink bug species

More difficult to kill than Southern green stink bug

This concludes Week Five of Cotton Insect Management 2011. The slide show can also be viewed at http://www.aces.edu/anr/crops/documents/CottonInsectManagement2011RonSmith.pdf

Cotton Insect and Crop Report - Alabama 2010

Cotton was planted on 345,000 acres in 2010, an increase of about 25% over the previous year. Over 96% of the acreage contained the RoundUp gene and approximately 90% contain genes for lep control. Due to the phase out of DP555, market share was gained by Phytogen, Fibermax and Stoneville varieties.

Early season insect pressure (thrips, aphids, cutworms, grasshoppers and plant bugs) was below historical levels for the second year in a row and very limited foliar applications were necessary. More than 80% of the acres were planted with insecticide treated seed, with the remainder planted with Temik in-furrow. Midseason pests included bollworms, at below normal numbers, which dictated fewer oversprays over the varieties with stacked lep genes. Very few lep sprays were made statewide, even in fields planted to conventional varieties. 2010 was one of the lowest pressure years in history for all lep species.

Stink bugs were by far the most economic of all cotton insects. Two to four foliar sprays were needed over most of the state to hold damage below threshold level. The dominant species in 2010 was the brown stink bug, Euschistus servus. The stink bug complex remains a complex issue to many growers and fieldmen, especially as it relates to scouting techniques and thresholds.

Weather during the production season was good until about July 15-20 at which time rainfall ceased and temperatures increased to 96-102° F (days) and 78-82° F (nights) for the following two months. This combination of heat and drought took its’ toll on yields since only about 10% of the state acreage is irrigated. Therefore, an 800-1000 lb potential yield deteriorated to about 500 lbs. Certain fields in several regions of the state yielded as low as 200-250 lbs of lint/acre.

Research continued in 2010 with the newer chemistries against the bug complex, sucking pests, and leps. Also, the newer genetic technologies were also evaluated both, agronomically and entomologically, within the state.

Cotton Insect Loss Estimates Made

2010 was one of the lightest insect years on record. Loss estimates range from a total of 5.2% of yield in central and south Alabama to 3.6% in the Tennessee Valley region. Most of these losses were attributed to one insect (pest) in each region. For the southern region it was the stink bug, predominately the brown species (3.5%), and for the north it was spider mites (2.3%). Other insects that caused measurable losses were the bollworm (lowest in 38 years), plant bug, and thrips.

Cotton

- A few late maturing fields are still being scouted for insects, primarily brown stink bugs and soybean loopers.
- Defoliation is proceeding on more fields each day and week.
- Harvesting has begun in a few locations. I observed a picker running about 8:00pm yesterday (9/2) in southeast Dallas county.
- Yield potential is all over the board (250 lbs- 1600 lbs/ac.)

Soybeans

A sub-threshold level of several caterpillar species can be found in most fields statewide. These include green cloverworms, soybean loopers, podworms, fall armyworms, and in the southern areas of the state, velvetbean caterpillars.

If the fall armyworms should occur at treatable levels, growers need to know that they are likely the “grass” strain which can be controlled rather economically with pyrethroids, Intrepid or Dimilin.

Stink bugs, especially the brown species, are at treatable levels in some bean fields. Growers should remember that stink bugs affect the quality of beans more so than the yield. Where brown stink bugs are the primary target, I would suggest a high rate of one of the labeled pyrethroids. These include: Baythroid XL, Brigade (Discipline), Prolex, Karate Z, or Mustang Max. Several of these have multiple generic brand names.

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.

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”?

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.

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.

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.

Tarnished Plant Bugs and Brown Stink Bugs

A few more fields have popped up with high numbers of adult tarnished plant bugs this week. These are fields that had low numbers in previous weeks. Even though the percent square retention is still above 80% now, controls are being applied to some of these fields to prevent the likely drop in retention next week. Another benefit of early controls would be to reduce the size of the infield population of immatures during the first half of July. Not only are these adults feeding on pinhead squares, they are also depositing eggs that will be hatching into TPB nymphs in a few weeks.

Brown stink bugs continue to be observed and reported from most cotton fields statewide. These adults will begin feeding on small thumb sized bolls as soon as the dried bloom drops off. In situations like this, we can have damaging economic levels of stink bugs prior to the third week of bloom. Two to three adult brown stink bugs per 20 sweeps (about 60 row feet) were captured in fields at the Wiregrass Research Center, Headland, AL this week. Remember that the life cycle of an adult stink bug may be as long as 30-35 days.