It’s the time of year when the peachtree borer (GPTB), Synanthedon exitiosa starts to emerge. There’s always a few “hotspots” around our growing districts. The signs of an infestation show up first as the tree starts to decline losing vigor. Next, entire trees may die. Within a few years the block really goes downhill in production and vitality. A check at the soil line reveals the telltale signs of gum mixed with frass where the borer has been feeding inside the tree.
The GPTB are striking clear-winged moths with yellow and steel-blue body markings. The adults of these insects have from one to four yellow-orange stripes across the abdomen, depending upon species and sex.
The GPTB enters the tree near soil level and does not require the presence of wounds or breaks in the bark for entry. This species pass the winter as borers (worm like) inside the tree.
In the spring the adult emerges as a moth that will lay eggs on the trunk during the summer. The GPTB shows up late June to early July; and stays active (laying eggs) through September. When the eggs hatch, the GPTB tends to crawl down the tree to soil level and will burrow inside. GPTB larvae can take two years to develop, so any control measure a grower would elect will require repeating for at least 2–3 years. Injury is caused by larval feeding on the cambium and inner bark of the trunk close to the soil level. Occasionally, larger roots are also attacked by GPTB. All ages of trees are injured. Young trees are at times completely girdled. Older trees are often so severely injured that their vitality is lowered and they are rendered especially susceptible to attack by other insects or by diseases.
Control for this pest are trunks sprays applied several times during the season and/or mating disruption using pheremones. It’s tough to beat the mating disruption program for GPTB using Isomate P. When this product is hung properly at a sufficient rate in mid-June to early July, it provides season long control. If you elect to use trunk sprays for control, here’s a few pointers:
Multiple applications are required. This pest is active from mid-summer to early fall. No insecticide applied once will give you long enough protection.
Use lots of water! This is a handgun operation. You need to create a barrier by spraying the lower portion of the trunk as well as the soil close to it.
Use the proper insecticide. The most common choice is Asana. Lorsban is also a good option. Be sure and read the labels regarding their use.
Have you ever considered spending some of your labor dollars on summer pruning? Every year there seems to be a gap between the end of thinning and the start of harvest. If you’re looking for a job to keep your crew busy, consider summer pruning. Both peach and apple require adequate light to form fruit buds. Excess shading in the lower portions of the tree result in the loss of potential fruit by flower buds turning vegetative. A few cuts in the upper portion of the tree to remove large water sprouts will open the tree to light. The timing of summer pruning is critical. It’s important to hit the “sweet spot” in mid-summer. Too early and vegetative regrowth will reduce the benefit. Being too late will add little benefit to the fruiting potential of the fruits and in worst situations it may reduce winter hardiness. The preferred time for summer pruning starts about 40 to 50 days after bloom for peaches and 50 to 60 days after bloom for apples.
I’ve noticed that the training of peach trees in Mesa county differ in a significant way than those in Delta county. It’s a common technique in Mesa County to use heading cuts, bench cuts to open up or spread the tree structure. If a person takes a Mesa county “gum” tour looking for cytospora canker you’ll quickly notice that most of the cankers are located at the site of a bench cut. Perhaps due to a bit less vigor in the higher elevations of Delta County, that cut is far less prevalent as is the presence of gum! This may be a valuable reason to summer prune. Send a crew through the block making only the heading cuts they would normally make in the dormant season. A bench cut at this time of the year will heal far more quickly, reducing the disease issue.
A number of apple blocks are taking a rest this year, a result from a huge crop last year. Any fruit system depends on the continued development of new fruiting wood. This is accomplished each year by pruning with “renewal” in mind. Young new wood must be encouraged as old tired wood is cycled out. Another tool that can be used to encourage heavy annual flowering in apple is the use of mid-season ethephon. Used at bloom or shortly thereafter, ethephon will encourage thinning. Using it close to harvest will encourage early maturity of the fruit. There is a window between bloom and harvest where ethephon will encourage developing buds to differentiate to a fruit bud rather than a leaf bud. This window occurs approximately 45 days after bloom to 50 days before harvest. Usually it’s sometime late June through July. The mid-summer codling moth cover sprays fall into this period.
1 pt of Ethephon per 100 gallons
Buffer the water to the acidic side before adding ethephon.
This is a concentrate application, don’t spray to the point of drip.
If desired, target spray to desired portions of the tree.
“People look at me incredulously when I point out that there is zero firm evidence to date that the neonicotinoid seed treatments are a serious problem! But the notion that all honey bee problems are caused by an insidious new insecticide resonates with a distrustful public , and has firmly established itself as “common knowledge.” But repeating something does not make it true! “
“It’s easier to fool people than to convince them that they have been fooled”
Did I get your attention with the paragraph above? I receive a number of calls through the season regarding bees and insecticide use. The quotes above come from a great article written by a research entomologist who is also a commercial beekeeper. Randy Oliver writes an extensive, well-documented article (27 pages) entitled “What happened to the bees this spring?” an expose on colony collapse. If you’re at all interested in the plight of the honey bee (as we all should be) it’s absolutely worth your time to read!
Here’s the link:
Grandevo is a new OMRI listed insecticide developed by Marrone Bio-Science. It looks to be a great new tool in the “organic” box. I’ve seen it used in a few blocks this year against green peach aphid with great results. In a conversation with a west Texas crop consultant he mentioned that they had used Grandevo with good results against weevil in an organic alfalfa field. Weevil can be tough to handle with conventional insecticides! It will be interesting to see what pests this material will be effective with. Here’s a bit of info from Marrone Bio Innvations website
GRANDEVO is naturally derived from a newly discovered bacterium, commonly known as Achromacil™, which produces a number of compounds that contribute to the creation of complex modes of action, resulting in a potent biopesticide that is highly active against labeled insects and mites. Control of pests is achieved by unique combinations of repellency, oral toxicity, reduced egg hatch, and reduced fecundity (ability of pest to reproduce). Grandevo has also been shown to maintain populations of most beneficials and introduced biological controls.
This looks like it will be a great tool to have around.
Remember, most (all?) of the organic materials require excellent coverage to obtain good results. To put this in perspective, think about black cherry aphid inside of a curled leaf at the top of a twenty foot tall tree!
Snake oil is an expression that originally referred to fraudulent health products or unproven medicine but has come to refer to any product with questionable or unverifiable quality or benefit. By extension, a snake oil salesman is someone who knowingly sells fraudulent goods or who is himself or herself a fraud, quack, charlatan, and the like. Every season there’s a long list of new products that get paraded through the front door at Cropworx. After listening to the sales pitch my first question is ALWAYS where’s your proof? Show me the independent research from an unbiased source. We work hard to bring you proven products that will add to your bottom line, not just ours!
“The budget should be balanced, the treasury should be refilled, public debt should be reduced, the arrogance of officialdom should be tempered and controlled, and the assistance to foreign lands should be curtailed, lest Rome become bankrupt. People must again learn to work instead of living on public assistance.” - Cicero 55, BC
As always! Please call me to discuss any of this information.