September 2013
If you plan on doing any soil fumigation this fall please let me know. ASAP!!! I need to place an order for Vapam. It’s a special order product and takes a bit of lead time. Thanks!
Last year at our Hort show Greg Reighard discussed the amount of sunlight needed within the tree canopy to produce quality fruit. Are your alleyways shade tunnels? Take a walk through different blocks before the leaves fall. It's a great time of the year to make a pruning plan to remove shade from your orchard. If you can't see through the “thicket” the sun can't either. Your sprayer can't penetrate those dense areas to deliver fungicides or insecticides to the top of the tree. A few large cuts here and there can greatly improve sunlight distribution and air movement within the tree! The fruit buds in the lower part of the tree will reward you for your efforts!
For a number of years I’ve discussed fall applications of urea to build bud strength for the following spring. The following is an email I received from Lynn Long of Oregon State University.
“Here is my annual reminder to apply a fall urea application. I know that many of you have been applying urea in the fall for some time, but what this research by Dr. Greg Lang of Michigan State University suggests is that there are benefits to applying a very high rate of urea. Two applications of 15-20 lbs. of actual nitrogen should be applied at one week intervals. Please note that this is 15-20 lbs./acre of actual nitrogen, not 15-20 lbs./acre of product. Last year there was also concern expressed about high temperatures at the time of application. When I asked Dr. Lang about this he responded that “the main uptake of urea comes in the first day of application; my colleague Eric Hanson (an OSU grad!), our nutrition expert, said he thinks it’s really mainly in the first 6 hours or so. So, as long as growers are putting the sprays out first thing in the morning, the late afternoon heat and volatilization probably doesn't affect the total amount that is likely to be taken up.”
In his research Dr. Greg Lang of Michigan State University has found that late summer or autumn urea sprays increased the shoot hardiness of the cherries that he tested and produced up to 20% larger spur leaves in the spring. As a whole, throughout the growing season, the spur leaves are the most important leaves for supplying nutrients to developing fruit. Greg speculates that if the spur leaves are larger than photosynthesis is increased and there are more carbohydrates being exported to the developing fruit. In his trials Greg applied two applications of low biurate urea as a foliar spray. An application on August 31 and a second application about one week later actually gave the best uptake of N into spur tissues and provided earlier acquisition of cold hardiness in the year that it was treated. However, application can be made up to leaf fall.
Each application should consist of 15 to 20 pounds of actual N/acre. Dilute sprays of 250 gallons/acre are possible, but some leaf burn at the leaf margin should be expected with these dilute sprays. Concentrate sprays ranging from 25 to 75 gallons/acre showed less phytotoxicity when applied with a curtain-type sprayer (small volume, small droplet size). The reduced toxicity which was noted with the concentrate sprays is probably due to less pooling of the material along leaf margins and therefore less burning of the foliage. It is also a good idea to apply boron in the fall. Studies show that there is greater boron uptake in the fall while leaves are still on the tree than during a delayed dormant application in the spring.”
Lynn E. Long
Oregon State University, Extension Horticulturist
Through the last of July into early August at my orchard in Cedaredge I recorded 14 days with rain totaling 6.9 inches! The summer monsoons really saved our bacon from an irrigation perspective! But a number of phone calls and visits this last week to look at peaches culled by Coryneum blight brought out the dark lining behind that silver cloud. So, it’s time for what’s becoming an annual reminder about a persistent problem, Coryneum blight. If you found blight marked fruit in your bins this year, starting your clean-up program this fall will go a long way towards a more profitable crop next year. The first autumn rains can start the spread of the disease. Infection can take place in the dormant season if proper moisture and temperature conditions occur. Spores, spread primarily by splashing water, can remain viable several months. The key to control is PREVENTION. This is especially true if you’re farming with organic methods. Establishing a protective barrier with copper is vital to keep Coryneum from germinating and spreading. Good sprayer coverage is important! The disease usually starts low inside the tree where moisture persists, so be sure and target this area. The most common application timing is at 50% leaf fall. How aggressive you need to be with rates and applications depends on if you need to clean up a problem or are just performing routine maintenance. A fieldman friend in Washington state mentioned that he has his growers add a sticker to all their Fall copper sprays. He said it's easy to still see the copper on the tree in February. The following quote comes from the 1996 Colorado Tree Fruits crop management guide. “Once established in an orchard, Coryneum blight is difficult to eradicate. Infected buds and twigs may produce spores for 2 to 3 years. A conscientious annual program of chemical control with particular emphasis on fall sprays and removal of dead wood is necessary over a 3-year period to alleviate the problem. Spring and summer sprays also may be needed until control has been obtained.”
As this season proved, Coryneum blight is very much a weather driven disease. A long wet spring, or a month full of summer monsoons, better turn your thinking to blight!
“A true friend is the greatest of all blessings, and that which we take the least care of all to acquire.” Lee Iacocca
Weed control in the tree row is much more than cosmetic. There is a measurable benefit to tree growth from the reduced competition for water and nutrients. Mouse populations are lower when there is little or no weed cover for them in the tree row The most economical time to control weeds, regardless of the material that you choose, is in the fall before leaf fall or with the leaves raked away, up until the ground is frozen. I once did an early December application in Cedaredge. The next spring you could see to the row where I had sprayed. This application will control the fall germinating annuals that otherwise will require treatment in the spring. Your VERY, VERY busy spring! Take a walk and look under your trees It is always easier and cheaper to prevent a problem than to cure it.
There are a number of residual herbicides available to cover a wide range of needs. From first year plantings to mature blocks, these materials reduce/eliminate weed competition in the area where they are applied. If you’re making a number of trips through the orchard each season with contact herbicides, consider a residual material.
The constant factors in safe and effective weed control are calibration, uniform coverage and timely incorporation of residual materials into the soil by irrigation or rain. Some residual herbicides can injure trees if the application rate is higher than the immobilizing ability of the soil and they are carried deep enough into the soil to contact tree roots. In other words, light soils are more risky than heavy soils. I know that a number of you use backpack or 4-wheeler tanks to spray weeds with contact herbicides. Using a hand wand to apply residual materials is risky at best. It’s next to impossible to get a uniform, proper amount applied. Some labels do not allow for application with a hand wand. Check to be sure your nozzle style and configuration delivers a uniform pattern on the soil surface. Account for the overlap that you will have in the center of the tree row. Don’t double the actual rate of applied material in this area by hanging extra nozzles or increasing nozzle size on the end of the boom.
Remove large weeds that prevent uniform spray coverage of the soil surface, the ‘shadow’ from existing weeds will be where your weed control will fail first next year. It’s best to not spray over the top of a heavy leaf drop; many of the small germinating annuals will be protected from the contact materials in the mix. If a windstorm moves the leaves before the next good rain, your residual material may be gone also. The cleaner the soil surface at the time of application, the more effective the material will be. Organic matter on the soil surface will bind up some of the material before it can get into the soil. If you still have irrigation water available, incorporate the material soon after application with an irrigation of ¼” - ½” . This will ensure no weather degradation and allow the residual control material to bind close to the soil surface where it is most effective.
If you irrigate with furrow irrigation, now is the best time to apply residual herbicides. Fall rains or snow will incorporate the material making an effective weed barrier for next season.
“The democracy will cease to exist when you take away from those who are willing to work and give to those who would not.” Thomas Jefferson
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