2009 Disease Advisory

Grasshopper damage and control options - by Greg Henderson, Edgefield, SC - June 19, 2009

grasshopper
Grasshopper damage
grasshopper
Grasshopper damage
grasshopper
Grasshopper damage
grasshopperCory Grasshopper

Above are a couple of photos of grasshopper damage I confirmed via Dan Horton today. I wanted to be sure before I commented. A good rule of thumb is that if you see grasshoppers in significant numbers, and they encroach from grassy orchard borders, hay fields, idle grassland (especially winter annual grasses that are drying down), it is a pretty easy assumption that feeding damage MAY be from them.
The spray guide does not address grasshoppers per say, however, Dr. Horton’s recommendation is any good pyrethroid will offer control
MAKE NOTE OF PHI’S (14 DAYS FOR ASSANNA….7 DAYS FOR BAYTHROID).
IMIDACCLOPRID has a PHI of 0 days for peach, but offers little control on grasshoppers….and a poor choice for stinkbug as well. (re. Dr. Horton). My apologies for those that this took a few days to get to.

 

Stink Bugs Moving to PeachesDan Horton & Phil Brannen, UGA, Athens & Ted Cottrell, USDA-ARS, Southeastern Fruit & Tree Nut Research Laboratory, Byron, GA - June 18, 2009

Stink bug migration into peaches, often from maturing wheat, has gone up dramatically. The numbers caught in some of Dr. Cottrell's traps (Fort Valley plateau) this past week have been impressive, up to 100 stink bugs/week/trap. However, each orchard is unique. Orchards surrounded by woods have far fewer stink bugs than orchards adjacent to wheat or separated from wheat by open ground.
Stink bugs are damaging in their own right, but their damage potential is greatly amplified by their ability to mechanically vector brown rot. While trapping is a powerful tool, frequent, close observation of all blocks gives any grower the ability to assess stink bug pressure. Check entire fields, but pay particular attention to field borders. Orchards adjacent to open ground, especially if that field or the next one over was planted to wheat may be particularly vulnerable.
Stink bug thresholds have not been developed for peaches. However, research shortfalls aside, growers still have to make decisions. My own, made up as I go, threshold lumps orchards into three groups:
1) None to a very few stink bugs,
2) More stink bugs than you saw on your last visit,
3) Lots more stink bugs than previously seen in 2009.
Given the brown rot risk associated with a wetter year and the widespread occurrence of varying levels of brown rot resistance, I encourage growers to spray stink bugs aggressively, even to consider stink bug-specific sprays. If stink bug numbers are rising, consider complete sprays (both sides of each row) for the orchard borders (especially adjacent to open ground and/or wheat). To moderate cost, I'd consider spraying the remainder of the orchard alternate-row-middle (directly spraying one side of each tree row by going down every other row middle).
Stink bug materials are at best mediocre. Irregardless of crop, we simply don't have good stink bug materials. However, on-going work by Dr. Cottrell, placing caged stink bugs onto sprayed peaches, is providing some indication of what materials are more likely to work. Unfortunately, even with the better stink bug materials, spraying more often appears more important than what you spray with.
Stink Bug Insecticides for Peach:
Assail 30SG/70WP 12 hours/7 days fair, a better option if Japanese and/or June beetles are also abundant
Baythroid 1EC
Renounce 20WP
Tombstone 2EC 12 hours/7 days, in cotton the 1EC formulation will often do a bit better
carbaryl 12 hours/3 days fair or worse, consider if you are too close to harvest to use a stronger material
Asana/Adjourn 0.66EC 12 hours/14 days @ 14 fl ozs/acre one of the better options, weak at mid-range rates
Beleaf 50SG 12 hours/14 days new, no better than pyrethroids in cotton, should not cause skin irritation often  experienced by applicators spraying pyrethroids
Proaxis
Lambda-T
Silencer
Taiga A
Warrior
Warrior II 24 hours/14 days similar to Asana at comparable rates
Imidan 70W REI/PHI based on package, as multiple labels are presently in the system, @ high, 4.5 lbs/a, rate performs as well as anything, weak at rates typically used in southeastern peaches
Mustang
Mustang Max 12 hours/14 days, Mustang is the more concentrated form, in cotton, Mustang is as good as any material
All stink bug materials should be applied at high rates, especially the pyrethroids. Spray often. To reduce cost, consider spraying ARM if there are not disease management considerations. Do not spray ARM in blocks with observable brown rot or in pre-harvest sprays.
All pyrethroids can cause rashes and dermal irritation to spray applicators. Individuals vary tremendously in susceptibility to pyrethroid-induced skin irritation. Based on the amount used, versus my perception of the number of complaints I receive, Asana/Adjourn may be a bit less problematic than newer pyrethroids.
If you have questions please contact your County Agent or your Extension Entomologist.

 

Having trouble getting Pristine? Here is a solution - by Phil Brannen, UGA - May 20, 2009

There were questions last week about the possible use of Endura and Cabrio (combined) as a replacement for Pristine, which can not be readily found in the market place.  I placed a call to Sandy Newell (BASF) on this, and he has worked the BASF system to make these products available for use this year.  The Endura product is the heavy hitter for brown rot, while the Cabrio component is much less active against brown rot.  If you want the true equivalent of Pristine, you can combine the products with equivalent rates of active on a per acre basis.  You might consider simply using the high rate of Endura, as this has generally been shown to be equivalent to Pristine in previous research trials; however, you do not have the resistance management provided by the Cabrio – something to consider.  I will put this out to the other county agents, etc. later today, but I do want you to know that this is now possible and legal.   
 
Thanks to Sandy Newell and BASF for their support in making the products available for your use this year.  Note that this use is time limited to this year.

Comment by Guido Schnabel: According to BASF representatives, these labels will expire at the end of 2009. Supplies of Pristine will return to normal in 2010. The active ingredients rates of Endura and Cabrio alone are equal to the rates in 14 oz rate of Pristine.

 

Consequences of hail damage and weed issues (May 14, 2009) Guido Schnabel -

There is no doubt, the hail will make the brown rot situation worse this year. Although the pictures were taken in an abandonded orchard in the Ridge area, brown rot is already showing in some commercial blocks. Again, when you see it, call your county agent and request the resistance test 'Profile'. This test will save you money, because you will know what the most effective spray program is for your particular area. 

One grower sprayed Gramoxone for weed control in his new orchard but still is struggling with horsenettle. According to Wayne Mitchum, our weed specialist, this weed is difficult to control but not very competitive.  "In trees that young the only option is to use Gramoxone but it will regrow. In older trees glyphosate may be used to suppress it."

hail1
Hail damage on early peach
hail
brown rot due to hail damage
horsenettle
Horsenettle
horsenettle1Cory Horsenettle survives Gramoxone

One of the otherwise clean operations had some plant losses (less than 0.1%) due to -what I believe was - Anthracnose crown rot.

Bacterial Spot and Pristine shortfall Issues for 2009 - Phil Brannen (May 8), UGA -
 
Bacterial spot is becoming a major issue for many varieties as the peach season progresses.  Rainfall and temperatures are now driving this epidemic, and if conditions continue as they have over the last month, we will have substantial disease.  We know that the period of susceptibility of leaf and fruit infection is greatest in the early part of the season, especially around shuck split and 2-3 weeks thereafter.  Fruit susceptibility to infection does go down over time, and fruit tends to become more resistant after the pit-hardening phase; however, it is likely that at least some infection can occur even after this stage of fruit development, so a season-long spray program will be needed if these conditions persist.  Oxytetracycline (antibiotic) products are active, but they are not as active as desired under these conditions.  Tenn-Cop at 4 fl oz/100 gallons is the only registered copper material for this time of the season, and there is a maximum of 6 applications per season with this product.  I think we need to initially consider combining both the Oxytetracycline and Tenn-Cop (mix in a minimum of 100 gallons per acre) in weekly applications for the moderately to highly susceptible varieties; copper damage can result, so be aware that good drying conditions are necessary.  It is a judgment call on other varieties, because as we learned in 2005, most peaches can have this disease in a very wet year.  This is a more expensive approach, but bacterial spot is also very expensive.  This program can be continued till 21 days prior to harvest.

Pristine, the fungicide produced by BASF, is a critical part of our brown rot management program for peaches.  There is currently a shortage of Pristine in the southeastern market (will likely continue through the summer), so I would highly encourage peach producers to find a source of this material as quickly as possible.

 

Anthracnose and gray mold thriving in some SC strawberry fields (May 8, 2009) Guido Schnabel -

One of three strawberry growers visited in the Upstate of SC had severe problems with Anthracnose fruit rot and gray mold. The field was dedicated to U-pick and therefore overripe fruit was present. In addition, the grower had sprayed primarily Thiram and Captan but none of the truely effective fungicides against those diseases. The other two commercial fields were clean of Anthracnose. Some gray mold was found sporadically. For Anthracnose AND gray mold control we recommend to spray Pristine OR Switch OR a mixture of captan and Cabrio OR a mixture of captan and Abound.

Anthracnose fruit
Anthracnose fruit rot
gray mold
Gray mold
Danny
Danny Howard
Cory
Cory Tanner

One of the otherwise clean operations had some plant losses (less than 0.1%) due to -what I believe was - Anthracnose crown rot. The grower was primarily spraying for gray mold (as he should) and did a good job with that. He now needs to incorporate Anthracnose protection. We recommended using Pristine OR Switch OR a mixture of captan and Cabrio OR a mixture of captan and Abound for the next 1-2 applications to stop the spread of the new disease and maintain a gray mold program. 

 

Anthracnose leaves
Leaf symptom; Anthracnose crown rot
Anthracnose crown
Anthracnose crow rot


 

Blossom blight and brown rot of peach; Cohere damage on strawberry (May 4, 2009) Guido Schnabel -

Watch out for brown rot this year. Blossom blight and green fruit rot are present. All we need is a wet June. Make sure you contact your local county agent at first sight of green fruit rot or mature fruit rot. He can do a resistance test that will tell you what to spray and what not to spray to get the most bang for your buck and to avoid a catastrophic control failure due to fungide resistance.  Check out the 'Profile' kit for details.

County agent Andy Rollins figured out that an overdose of Cohere sticker used with an Elevate/Captan spray for gray mold caused a devastating discoloration of strawberry fruit. Here is his report:
"On Monday, May 11th between 12 noon -1pm a upstate grower sprayed his strawberries with 72 oz./ A Captec, 1 lb./A  Elevate and 32oz/A Cohere.  The same exact spray was used Sunday, May 10th at 8-9am without any problems.  Unfortunately, the application on the 11th resulted in severely damaged ripe and green fruit that showed up Tuesday morning when I was called to help figure out the situation.  I could tell it was chemical damage but I didn't know what  which product caused the burn.  On Wednesday, May 13th I mixed up the same concentration of each product used separately and applied them at the same time of day (12-1pm,  It was warm that day as well but not quite as sunny) to approximately 35 ft of row using a 1 gallon pumpup sprayer.  The treatments were 1=captan 2=elevate 3=captan +elevate 4=cohere at label rate 5=cohere at the rate the farm applied.
After 24 hours, I checked my plots and the damage was replicated identically only in treatment row 5.  The grower read the label and it clearly states that you can use upto 1 quart (32oz) per 100 gallons of Cohere.  Unfortunately, he didn't read/understand the next sentence which clearly states to not us more than 10 oz/A.  Since the grower was putting out 100 gallons/A he was applying more than 3 times the label rate of Cohere.  Thankfully, now the plants have grown out of it some and he has some undamaged fruit coming from the damaged area."

In some areas I saw peaches that were half chewed up. Most likely squirrel damage due to the fontness of these animals for seeds and pits. Last but not least, Peach Tree Short Life is still around. The picture below was taken from an orchard on the Ridge. Ring nematode count turned out to be more than 120 per cc soil and rootstock was something different from Guardian.

Cohere
Cohere damage
squirrel
Squirrel damage
greenfruitrot
Green fruit rot
ptsl
PTSL

 

Phomopsis twig blight and bacterial canker epidemics (Saluda and Edgefield counties, SC; April 15, 2009) Guido Schnabel -

The year 2009 is the year of Phomopsis twig blight. I have never seen that much damage from that disease. Depending on the variety, the damage (twig die-back) is anywhere between 5 and 70%. Varieties that were hardest hit: Marsun, O'Henry, Redglobe, Flameprince, Julyprince. Age of the trees did not seem to matter. Growers remembered a severe rain-storm during the fall of 2008 (the fungus infects during leaf fall) that dropped most of the leaves and spread the fungus. That could explain the epidemic. For more information about Phomopsis twig blight and its management, click here; pdf.

There was also a significant amount of bacterial canker killing scaffold limbs and entire trees. The foul smell of the affected bark was very prevalent. The disease is often associated with nematodes, especially the ring nematode. We do not see it often on Guardian rootstock, though, because it is resistant to ring. For management suggestions, check out Dave Ritchie's bulletin. Also, I recommend to be extra careful to not spread the disease during winter and summer pruning. In blocks with cankers, dip loppers and saws in a 10% bleach solution not only between blocks but also between trees.

phomopsis
Phomopsis twig blight
bcanker
Bacterial canker
Bcanker
Bacterial canker
Greg Henderson
Greg Henderson

 

Freeze injury, Phomopsis twig blight, deer damage, strawberry petal injury (Landrum, SC; April 13, 2009) Guido Schnabel -

Freeze damage and Phomopsis twig blight were the main issues during the trip to the Landrum area. Temperatures down to 28 F on April 07 damaged the peach crop in many orchards (see picture below). Phomopsis twig blight caused about 50% of the fruiting wood to die in an established (8 yr old) Sureprince orchard in Chesnee. Deer damage occurred on young trees. Some trees were completely destroyed. For deer management suggestions, click here.

Strawberries - One grower had sepals of strawberry fruit wilting. Did not look like angular leaf spot (no translucent lesions, no defined necrosis of compartments). Botrytis was suspected. After three days of incubation in a moist bag, there was no biotic activity. No spores forming, no bacterial flow under the microscope. My best guess: This used to be a gray mold infection but was cleaned up with an application of Switch (4 days prior to my visit). Don't think it is chemical damage (copper toxicity) either. Symptoms are not supportive.

phomopsis
Phomopsis twig blight
deerdamage
Deer damage
frostdamage
Frost damage
petaldamage
Petal damage

 

Phomopsis problems in established and nearby young orchard (Ridge, SC; April 3, 2009) Guido Schnabel -

Concerns about twig die-back in an established and a nearby young orchard located on the Ridge in SC were investigated. Quite a bit of rain fell during bloom and consequently we found blossom blight in the established orchard (picture 2). In that orchard Gummosis was also established causing gumming on the trunks and scaffold limbs (Picture 1). The young orchard with 2-year old trees had not been treated with pesticides. Most twig die-back in both orchards was due to Phomopsis twig blight (picture 3). For Phomopsis management options click here (Constriction Canker Article). Some twig die-back was not related to fungal infection and may have been caused by insect damage (fourth picture).  On some of those twigs a dead insect was still attached to it.

The outbreak of Phomopsis twig blight in particular in the young orchard raises the question as to whether fungicide sprays are needed in the first two years of establishment. My opinion: if there is an older orchard nearby with significant Phomopsis problems that can spread the diseases to the younger one: absolutely justifyable.

The blossom blight in the older orchard is a reminder that growers need to stay on top of their brown rot spray program. At first sign of green fruit rot, contact your county agent for the free-of-charge fungicide resistance testing service called 'Profile'.

trunkgummossis
Gummosis on trunk
blossom blight
Blossom blight
pycnidiaontwig
Phomopsis on twig
PTBadult
Insect on dead twig tip

 

Brown Rot Green Fruit Rot and Scab (March 31, 2009) Guido Schnabel -

If the weather stays moist, you may want to choose captan over sulfur in your cover sprays. Captan is the better material for scab and green fruit rot control and may even have some additional effect on bacterial spot control if applied in tank mixture with oxytetrocycline (e.g. Mycoshield). That latter statement is based on lab studies out of Biglerville, PA confirming a synergistic interaction of captan and an antibiotic.

 

Bacterial Spot (March 27, 2009) Dave Ritchie –

Conditions for getting bacterial spot started this spring have been almost ideal. Temperatures have been a bit cool but the moisture periods have been lengthy and temperature apparently has minimal effect on bacterial dispersal as long as it has been warm enough for the bacteria to have multiplied, which has occurred. Samples from spring cankers (taken week of  March 16) that develop from the bacterial overwintering sites in buds have yielded very high populations of the bacterial spot pathogen, thus inoculum is present. Growers who have followed the dormant to bloom copper spray program have done the best that is currently know and hopefully this will reduce fruit losses to bacterial spot.

What to do now? Growth stage likely ranges from bloom to petal fall with possibly some early shuck split. This is the start of the most susceptible stage for fruit to become infected. My recommendation as soon as this rain (March 26 – 29) is past is to apply a tank-mix of copper plus oxytetracycline. Use the metallic copper equivalent (MCE) of 0.25 lb (examples: Kocide 2000, OR Kocide 3000  12 oz of product; OR Cuprofix Ultra 40 at 10 oz of product OR another copper product such as TennCop at 6-8 fl oz) per acre in 100 gal water plus 1.0 lb of a 17WP Mycoshield 17W, OR FlameOut 17W, OR FireLine 17W. Although copper acts as a protectant, there is some research data that suggests that an application of copper soon after rainfall may still have a beneficial effect.

The copper will most likely result in some leaf injury in the form of spots with some dropping of these leaves occurring. As always when spraying copper materials on peaches, before making a subsequent copper application, check for the amount of injury that may have occurred from previous sprays. Also, make sure that the sprayer is properly calibrated and that the amount of copper material is correctly measured. Be very careful with the use of copper sprays on peaches after shuck split (the 0.25 lb MCE is TOO MUCH) – excessive injury can easily occur. The alternative, bacterial spot diseased fruit, is not good either. If infections have occurred during this rainy period, look for disease symptoms on leaves in about 7-10 days, sooner if temperatures go into 70sF or higher. On fruit, symptoms should be visible in about 2-3 weeks. Hopefully, you won’t see any!