Category Archives: Entomology

Cotton Coming Up, Variety Trial Planted, Scout Thrips

Cotton is anywhere from just planted to cotyledon to 4 leaf at this time. Recent rains have growers planting and we hope to have more this weekend. It’s past our thrips date of May 10th and we have reason to believe thrips may crash soon this year – since we had a warm winter, they were active sooner. But remember, thrips live in the winter weeds along roadsides and move to our cotton and peanuts following germination.

From 0 to level 5, I’m seeing damage from none to about level 3, sporadic in most fields. Neonic seed treatments (imidacloprid, thiametoxam) are active on thrips for up to 14 – 21 days after planting. If we have no seed treatment, we need to be in the field checking the first true leaf. This is the best time when we need to apply a foliar application. Once we have 4 true leaves and the plant is growing fast, thrips foliar sprays are not economical.

Thrips injury on 1st true leaf

Threshold

Research has shown that foliar applications are still needed when thrips infestations are high. The best way to make this decision is based on current threshold of: 2 – 3 thrips per plant AND/OR presence of immatures. The immature (wingless) thrips will be yellow/green in color; the adult (winged) thrips are black. Take a white piece of paper and slap a plant on it. Give it a second for the thrips to start crawling. In this field, I have immature thrips present. This suggests are at-plant insecticides are no longer active, and reproduction is taking place.

Here is a note from UGA Extension Entomologist Dr. Phillip Roberts from 2016. It may still answer some question today:

Should we follow with a second acephate spray? Dr. Roberts has conducted trials with 1 +3 leaf sprays, and they showed no difference from a 1 leaf ONLY spray. Something I noticed rating our thrips trials (2016) is not only the effectiveness of 1 leaf sprays, but also how fast the plants grow in 14 days. If we have a timely insecticide spray, AND growing conditions are good, cotton will outgrow potential thrips issues. The only reason to consider a second foliar application is if 1) cotton is not growing fast 2) thrips are still highly active. It would be a judgment call at best.

How long does this foliar spray of orthene last? Research entomologist Dr. Michael Toews, and Dr. Roberts have data on this that hasn’t been totally put together, but the best analysis is maybe 3 -4 days. Pyrethroids, on the other hand, photodegrade fast. Dr. Roberts says pyrethroids will kill thrips, but the reason we do not recommend them is 7 days after treatment, thrips populations are higher where pyrethroids were sprayed than where orthene was sprayed.

We were able to plant our variety trial last Friday. I visited the field today, and cotton is just now coming up. The field is at the end of Centennial Road where it touches Airline Road. It is the one on the right. We ended up participating in the UGA On Farm Variety Trial. Most of the varieties I asked for were in the trial. We were able to get in all varieties I wanted plus these for a total of 15. We replicated three times in the field; reps are actually stacked on top of each other.

2017 UGA On-Farm Variety Trial

We got done real fast, thanks to Brandon’s precision planting. Thanks to growers Mike, Brandon and Chandler Barnes for planting the trial this year and Jodie Stringer (Boston Gin) for helping and Jessica Jones, owner of Barbaritoes, for feeding us in the field.

Jodie and Brandon fixing flags

Brandon Barnes, Mike Barnes, Chandler Barnes, Jodie Stringer, Andrew Sawyer

 Jodie and Brandon fixing flags

Leave a comment

Filed under Cotton, Entomology

Satsuma Insect Issues

This may not be the case everywhere, but here we avoided some serious freeze injury on our 3 year old trees. These satsumas are going on 4 years old, so next year is the year we hope to harvest these. Some of these fruit are pulled off the tree this year to allow the tree to focus on vegetative growth.

Leafminers

We haven’t been hit too much with leafminers here, but in other parts of the county and with younger trees, damage is evident. It’s difficult to drench imidacloprid to time killing the initial infestation. Lowndes County Ag Agent Jake Price says this about leafminers and leaf footed bugs:

Leaf miners are starting to emerge. Usually our first flush is safe from leaf miners but they can be a problem at the end of the first flush and every flush thereafter. If you had frost damage and your trees are flushing again, you may want to go ahead and make a treatment. Imidacloprid drenches last about two months. Micromite and Ari-Mek are also labeled to control leaf miners if you are having issues with mites as well. If you do make a foliar application of anything, try to wait until all your blooms are gone as to protect the bees.

Mining trail from leafminer fly. Egg is laid on leaf. Larvae hatches and goes under leaf cuticule where it mines, curling the leaves and comes out to pupate. This one came out where my thumb is.

Leaf-footed Bug

A second insect I have been seeing is the leaf footed bug or what many call “stink bugs”. They can damage fruit and cause them to drop from the tree.  Now they are feeding on young blooms and shoots. I see these insects on a variety of things from muscadines, cotton, soybeans, peaches, plums, and blueberries, etc. They tend to congregate on certain trees. In general, I do not think these are a major pest of Florida citrus but they look like they will be a problem in satsumas because they damage fruit.  Again thoughts are no control is needed at this time unless you just have them throughout your grove.  If needed you may want to treat certain trees where they tend to congregate.

Leaf-footed bugs – Photo: Doug Collins

Leave a comment

Filed under Citrus, Entomology

2017 Sugarcane Aphid Management In Grain Sorghum

Sugarcane Aphids

Here is the newest management prodecdures for sugarcane aphids in grain sorghum from UGA Extension Entomologist Dr. David Buntin:

1) Plant early – Because the aphid migrates northward in the spring, early plantings may avoid may avoid very large infestations.   Late planted double-crop plantings are at greater risk of severe infestations.   

2) Plant a tolerant hybrid/variety – Some hybrids have been shown to have some partial tolerance to the aphid.   This table from the Sorghum checkoff program and ratings for the Georgia Statewide variety trial lists grain sorghum hybrids with some degree of tolerance to SCA.   In my own trials the most tolerant grain types were in alphabetical order Alta AG1201, Dekalb DKS 3707 and DKS 4807, Pioneer 86P20, Sorghum Partners 73B12 and Warner W-7051 (tall, late variety).

http://www.sorghumcheckoff.com/farmer-resources/grain-production/hybrid-selection

http://www.swvt.uga.edu/2016/sysr16/AP103-8-sr-resist.pdf

Sugarcane aphids populate under grain sorghum

3) Use an insecticide seed treatment – My trials last year found that insecticide seed treatment would limit seedling infestations for 30 – 40 days after planting.   All registered neonicotinoid insecticides are effective including thiamethoxam (Cruiser), clothianidin (Poncho, NIpsIt Inside) and imidacloprid (Gaucho, others).   Most grain sorghum seed was treated with one of these seed treatments in 2017.

4) Scout early and often – Fields can quickly be inspected for the presence of aphids by looking are on the underside of leaves.  Once aphids are detected, scout at least once, preferably 2 times per week, because aphid numbers build very quickly.  Shinny lower leaves with honeydew are a clear sign of infestation. 

5) Beneficial insects usually do not control infestations – SCA and their honeydew attract large number of beneficial insect predators such as lady beetles, syrphid fly larvae and lacewings.  A parasitic wasp is present in and caused infested aphids to turn a dark blue-gray color.  No aphid fungal disease has been observed either.  Generally the rapid rate of increase in aphid populations overwhelms the beneficial insects and severe plant damage usually occurs. 

6) Treat when aphids reach threshold levels – The current threshold is 50 or more aphids per leaf on 25% pf plants preboot stage through dough stage.  Once threshold is reach do not delay application because infestations can very quickly go from the threshold level to 100% infested plants and hundreds of aphids per leaf.  

7) Use an effective insecticide – PYRETHROID INSECTICIDES ARE NOT EFFECTIVE and may flare infestations by killing all the aphid predators.  Regardless of the insecticide, rapidly expanding populations are difficult to control.  Foliar insecticide options for SCA in Georgia are:

  • Sivanto Prime (Bayer Crop Protection). Sivanto prime has a full section 3 label and a supplemental 2ee label for lower rates on sorghum and other grain crops. The 2ee rates are 4 – 7 fl. oz per acre. Sivanto was very effective in my trials at rates of 4 to 7 fl. oz. per acre with Control usually lasting 21 days or more. At the 4 oz rate it can be applied up to 7 times during the season but has a 21 day PHI.
  • Transform WG (Dow AgroSciences). Transform WG federal label was re-instated last year but sorghum is not on the full federal label. But Transform WG has an approved Section 18 emergency exception for use on sorghum in Georgia in 2017 but the label has not been issued yet. The label will allow for 2 applications per season and not more than 3 oz per acre per crop and has a 14 day PHI. Transform cannot be used during bloom to protect pollinators. In my insecticide trails last season, rates of 1.0 and 1.5 oz per acre were effective. Use the 1.5 oz rate if aphid populations are increasing rapidly.
  • Chlopyrifos (Lorsban Advanced, Nufos, other).   Chlopyrifos is labeled at 1 to 2 pints per acre. The 2 pint rate has a 60 day harvest interval. The 1 pint has a 30 day harvest interval, but is usually not effective. The 2 pint rate was 60-90% control for about 10-14 days. At the 2 pint rate it cannot be used after the boot stage due the 60 day PHI. DO NOT USE CHLORPYRIFOS ON SWEET SORGHUM.
  • Dimethoate ( Dimethoate, Cygon). Not recommended. In my trials dimethoate is variable in control and control if it occurs is only for a week or so.  

8) Good coverage is key to effective control.  Use tips and GPA for maximum coverage especially lower in the canopy. A minimum of 10 gpa by ground and 5 gpa by air is highly recommended.

9) Avoid pyrethroid insecticides for other sorghum pests.   For sorghum midge try to avoid routine pyrethroid sprays for sorghum midge.  Instead scout and treat at 1 adult per panicle.  Chlorpyrifos (1 pint per are) for low to moderate infestations.   If pyrethroids are used they can be tank mixed with Sivanto (Do not use Transform during bloom). Early plantings often avoid serious midge infestations.  For fall armyworm in the whorl, the threshold is 50% infested whorls.  Use Belt, Prevathon or Lannate which are specific to caterpillars.  For headworms, corn earworms fall armyworm, sorghum webworm, the threshold is 1 worm per head and use Belt, Prevathon, Beseige or Lannate.

10) Check fields 2-3 weeks before harvest for infestations.   A treatment may be needed if large numbers are in the head to prevent damage to combines.  Hybrids with taller stalks and more space between the grain and upper leaves may make harvest easier by reducing the amount of leaf material going through the combine.  Large infestation producing large amounts of honeydew and sooty mold may interfere with harvest desiccants.  Transform WG can be applied up to 14 days before harvest.  

11) Silage/forage sorghum control. No work was done specifically on SCA control in silage/forage sorghum.   So the same recommendations for grain sorghum also apply to silage and forage sorghum.   Both Sivanto prime and Transform can be used on silage and forage type sorghums.   Grazing / hay interval is 7 days for both products.  Chlorpyrifos at 2 pints per acre has a 60 day grazing forage, hay interval so is usually not an option for forage and hay sorghum.  In forage/hay types, the later cutting were damaged last year.  Spray coverage is difficult when plants get tall.  If aphids are present but below threshold consider a spray application as late as possible before the crop gets too tall.

12) Sweet sorghum. Sivanto prime, Transform and chlorpyrifos cannot be used on sweet sorghum. There currently are no effective treatment options for sweet sorghum. A section 18 request for use of Sivanto prime on sweet sorghum has been submitted to Us-EPA but the request is still pending.

Leave a comment

Filed under Entomology, Grain Sorghum

Thrips Infestation Predictor For Cotton

At our cotton meeting, UGA Extension Entomologist Dr. Phillip Roberts talked about a new model to help predict thrips infestation. The Thrips Infestation Predictor for Cotton tool can be found at http://climate.ncsu.edu/cottonthripsrisk/ . Dr. Roberts has this to say about the model and scouting:

Thrips are the most consistent insect pest of cotton in Georgia and the southeast.  Near 100 percent of the cotton planted in Georgia will be infested by thrips each year.  Preventive insecticides applied as a seed treatment and/or infurrow application at planting for thrips control provide consistent yield responses.  In some situations supplemental foliar insecticides may be needed in addition to preventive treatments at planting. 

Plant injury from thrips is a function of thrips pressure and seedling growth.  The Thrips Infestation Predictor for Cotton (TIP) tool uses planting date, temperature, precipitation, and knowledge of when and how intense thrips infestations will be to predict risk of thrips injury to cotton.  The TIP model can be used to identify planting dates which are at greatest risk for thrips injury.  The TIP tool will give the best predictions within 10-14 days after you use it, so use at multiple times during the planting and thrips management season would be beneficial.  Dr. George Kennedy has prepared the webinar “Thrips Infestation Predictor for Cotton: An Online Tool for Informed Thrips Managment”.  The webinar includes an overview and how to use the TIP tool and can be found at http://www.plantmanagementnetwork.org/edcenter/seminars/cotton/ThripsInfestationPredictor/

High risk planting dates will require more aggressive thrips management compared with low risk planting dates to achieve acceptable thrips control.  Management options for high risk planting dates would include the use of infurrow liquid insecticides such as acephate, imidacloprid, or aldicarb or the use of a neonicotinoid seed treatment plus a supplemental foliar application at the 1-leaf stage.  In low thrips risk environments neonicotinoid seed treatments will generally provide acceptable control.  The TIP tool should allow proactive decisions to be made relative to thrips managment.

How confident should I be using this TIP tool?  My thoughts are exactly as those of my colleague at NC State who answered this question very well.  Any forecast will have some uncertianty.  However, this tool is based on many years of data from across the Southeast US Cotton Belt and has been validated several years since.  We are very confident that this tool, when used as instructed, will accurately forecast thrips risk in cotton.

The TIP tool will not replace scouting and sampling for thrips and thrips injury in cotton.  But it does provide information which will improve our thrips management programs.

Leave a comment

Filed under Cotton, Entomology

Pecan Irrigation & Early Insects

We are now seeing budbreak on our older trees. UGA Extension Pecan Horticulturalist notes that our budbreak timing is pretty close to last year – thanks to the cooler weather of a couple of weeks ago. Pecans across the state narrowly missed serious damage from the freeze. We won’t know about young trees until May or June. In Thomas County, it doesn’t look like the duration was long enough to have a major effect.

Dr. Wells points out though budbreak has begun, he is concerned that it may be somewhat uneven as a result of the warm winter. This could affect pollination. With the arrival of budbreak, there are other things to keep in mind.

Irrigation

It has been abnormally dry in south Georgia for weeks, and the trees will need water as they wake up. Mature trees should be irrigated at 17-18% of full capacity at this time. Young trees in the 1-3 year old range need about 4 hrs every other day throughout the season beginning now. Rain is in the forecast for Friday so if you receive a 1″ rain or more, turn the irrigation off for 3 days.

Pecan Budmoth Damage- Photo by Dr. Lenny Wells

Budmoths

Be on the lookout for budmoths in young trees. They begin feeding soon after budbreak and can destroy the buds making it difficult to establish a good central leader. Treat with chlorpyrifos, a pyrethroid, Intrepid, or Dimilin as needed.

Phylloxera

Phylloxerra damage was particularly severe last year. If you plan to treat for Phylloxerra, do so now for those varieties that have started to break bud. These treatments must be made when budbreak begins or you will miss the window for treating them. Chlorpyrifos or imidacloprid are the materials of choice.

You can read more about Pecan Leaf Phylloxera on this blog post from last year.

Galls from Pecan Leaf Phylloxera

Leave a comment

Filed under Entomology, Pecans

Ambrosia Beetles: First Flight

Cook County Ag Agent, Tucker Price, called me this week to report seeing the first flight of ambrosia beetles. For us in deep South GA, the first flight is usually late February. UGA Extension Pecan Horticulturalist Dr. Lenny Wells has this information:

Ambrosia Beetle - Photo by Dr. Lenny Wells

Ambrosia Beetle – Photo by Dr. Lenny Wells

We’ve had reports of ambrosia beetles attacking young trees in south GA recently. This is no surprise with the very dry late summer/fall and very mild winter we’ve had.  The severe weather lately will likely make trees more vulnerable than usual where flooding rains and wind have really stressed some orchards. Trees that stand in water for long periods, especially when they are breaking bud and trying to leaf out, are very attractive to the beetles.  Growers should be checking young trees regularly for frass toothpicks that indicate ambrosia beetle attack. It is also a good idea to have some traps out around those young orchards so you will know when the beetles are active. Cold weather will slow or stop the beetle flight temporarily, but we can probably expect to see activity pick back up as soon as warmer temperatures return. See link here for description of management.

Anyone planning to plant trees this year should try to get the trees in the ground no later than mid-February to aid in recovery from transplant shock before budbreak and warm weather arrives. Trees planted late become more stressed and have a harder time recovering from transplant shock.

Leave a comment

Filed under Entomology, Pecans

More Bark Beetle Attacks?

With the persistence of this drought, we may see more bark beetle attacks. For the first time, I witnessed two Ips engraver attacks on the same property. The two attacks occurred four weeks apart. The scenario required for Ips attacks is not usually reoccurring. Because they attack only stressed trees, Ips usually leave the scene and are done. Could it be that stress from the drought is causing trees to release the stress pheromones that attracts the beetles?

Ips Engraver Beetle-UGA

Ips Engraver Beetle-UGA

There are a few species of beetles that cause problems in pine stands. The Southern Pine Beetle and Ips Engraver Beetle bore into trees and induce the blue stain fungus. This fungus clogs the vascular tissue of the tree and kills it. The difference in the two species is that Ips beetles rarely if ever attack a healthy tree. Pheromones (chemical signals) from a dying or distressed tree are picked up by Ips beetles. These are usually lightening struck trees. Once Ips beetles show up, they only attack a few trees and leave. Sometimes I see 3 trees in a stand killed and as many as 8 trees killed last week.

Symptoms/Signs

Other than a tree that suddenly dies,  the most common sign of an Ips attack is pitch tubes on the side of the tree. Once the adult beetle bore into the tree, the tree exudes sap to counter the beetle. The sap piles up and look like pieces of bubble gum attached to the tree. The center of the tube contains a hole through which the adult beetle enters the inner bark. If no hole is present in the pitch tube, the beetle attack was unsuccessful.

Boring dust and pitch from Ips attack

Boring dust and pitch from Ips attack

PitchTubes (2)

Holes in pitch tubes where adult beetles entered the tree

An addition to the presence of pitch tubes, the adults construct egg galleries in the inner bark. These galleries are in certain shapes. Ips usually follow the wood grain, and have a “Y”- or “H”-shaped gallery patterns. I took my knife and scratched some outside bark away to find a few galleries.

Egg galleries of Ips beetle attack

Egg galleries of Ips beetle attack

Management

A common question is should we cut the trees down? Shortly  after the initial attack, needles at the crown turn yellow then brown. This happens quickly. Once we notice the trees are dead, the Ips beetles have already moved out. UGA Extension Forestry Specialist Dr. David Moorhead says in a pine stand, we actually do more damage cutting down a few dead trees than if they are left alone. The only time we would cut down trees is for 1) astetic reasons or 2) they pose a risk if fallen.

We can also use insecticides, but the issue is Ips attacks are difficult to predict and they enter the tree high up – you would have to cover the tree. The third beetle species is black turpentine beetles. They attack trees at the base and move about 5 feet high. However, their risk is minimal since they do no carry blue-stain fungus.

Cross section view of blue stain fungus

Cross section view of blue stain fungus

1 Comment

Filed under Entomology, Forestry