July 2007
If you're interested in doing leaf analysis late July through August is the time. To take a sample, pull 50 leaves from the middle of this seasons terminal growth as you walk randomly across the block. Place the sample in a paper bag with your name, the variety, and block number or name. Albion Labs has offered to do a number of free samples. Please note Grand Mesa Discount as your dealer. Send your samples to: Albion, 101 North Main St., Clearfield UT 84015. They will run the tests then send you the results. This fall we'll have a meeting to review your results and plan a nutrition program. For more information take a look at Albion's web site. www.albion-an.com
I've looked at a couple of pest problems lately that raise an important concern. The first is with pear psylla control using Agri-Mek. If you've used the low end of the rate (or below) for a number of years, survey your block for psylla. It's possible that the low rate will not last the season. The other issue is with mites. With the heat we've had lately mites are showing up. Take a morning before harvest hits full steam and look for any problems that may be coming.
If you had mildew problems in your cherry crop now is a great time to deal with it. Here are two programs available to you, both have been effective in research trials. Oil @ 1%, 100 - 200 gallons per acre will kill the mildew that it contacts. If done soon enough after harvest this will reduce the numbers of cleistothecia formed, reducing the amount of overwintering spores. Coverage is the key. Drive slowly enough to let your sprayer fan completely displace all of the air in the center of the tree with the spray mist; there are a lot of mildew colonies in there. Driving speed in a full sized orchard should be 1 to 1 ½ mph. If you miss the oil timing and cleistothecia (those little black pepper spots you can see in the mildew colonies) are already present in high numbers, wait until just prior to leaf drop in the fall. Lime-Sulfur @ 2 gallons per acre, applied full dilute (400 gpa) will destroy over 90% of the cleistothecia that it contacts. Coverage is the key for both of these materials.
“Be careful about reading health books. You may die of a misprint” Mark Twain
Most insect and disease problems originate and spread from the center and upper portions of the tree where your spray coverage is the poorest. No contact — no kill. Good coverage is essential to good control. Gallonage per acre and coverage are not necessarily related. Coverage is directly related to the ability of the fan on your sprayer to replace the air in the tree canopy with air from your sprayer. The smaller your fan — the bigger the tree — the lower your horsepower — the higher the days breeze — the slower you have to drive to get complete air replacement in the center of the tree canopy. The smaller the droplet size the more likely it is to stay in the air stream all the way into the center of the tree and settle on your target. Improve your coverage of this problem area by slowing down, and calibrating for smaller droplet size. If you have flip over nozzles, use #25 swirl plates and a larger disc orifice instead of #45 swirl plates and a small disc orifice.
While I'm on the subject of spray coverage.... Take time to look at your tree canopy. Mid summer with a full set of leaves quickly reveals how dense the foliage becomes. Plan your “big” cuts for next winter now!
Want to know your exact acreage? How about trees per acre at a given spacing? Here's the formula:
tree spacing x row width = A; 43,560 (sq ft in an acre)/ A = trees per acre. Example: 6 x 16 = 96,
43,560 / 96 = 453 trees per acre. Count the number of trees in the block, divide by your answer (453) to arrive at the total acreage.
With more and more materials going on at rates of a few ounces per acre its critical to know your exact acreage!
Your peach tree crown borer (CB) control program should be up and running. If a single trunk spray is your sole means of protection, keep a close watch at the base of your trees for damage. Crown borer is active from mid summer to early fall. There's no insecticide available with that long of a residual. If you or a neighbor has a CB problem you should consider an August application. I know, I know... it's harvest... you're too busy. That's one of the reasons Isomate P is so popular. What ever method you choose, make sure it's adequate! KEEP LOOKING DOWN!
Think the proper chelate is important when choosing a nutrient? GMD has a 13% iron chelate (EDTA) material that sells for about half the cost of another that's only 6% (EDDHA). At first glance a person would wonder why buy the 6% for more money? The cost difference is the chelation agent. The key to results is in the chelation agent. Different soils, different applications, require specific types of chelation agents. In this case the cheaper, more potent material is far less effective.
Chelation is the process of attaching a specific organic molecule called a ligand to a mineral ion at two or more sites to form a ring structure. Chelates can be either synthetic or naturally occurring. EDTA, DTPA, EDDHA and similar molecules are examples of synthetic chelating agents. Amino acids, hemoglobin, and chlorophyll are examples of naturally occurring chelates. Solubility in water is essential for absorption by plants. This is true of the systemic chemicals as well as nutrients. Insoluble mineral salts, including all oxides, most hydroxides, carbonates and phosphates, and some sulfates cannot be absorbed by the plant. When applying nutrients to the foliage, it is very important that the nutrients are in a form that is available to the plant. The surface of a leaf is negatively charged. When soluble forms of minerals are applied, most of the mineral ions (positively charged) are attracted to the negatively charged leaf surface and do not get into the vascular system of the plant. In order for the plant to translocate the minerals applied, they must be delivered to the vascular system. Cell membranes do not have the ability to absorb synthetic chelates such as EDTA, DTPA, and EDDHA. For the mineral to be absorbed into the cell, these chelates must release the mineral. This leaves a vacancy in the chelate molecule displaying charges that must be satisfied. EDTA, for example has a very high affinity for calcium. As a result it will scavenge calcium from the surrounding environment, including cell walls and membranes. This is the reason that the foliar application of high concentrations of EDTA often result in phytotoxicity. Amino acid chelates are neutral in charge. They are neither attracted to nor repulsed from the negatively charged leaf surface. Consequently, they freely pass through the cuticle. When an amino acid chelate reachs the cell membrane, it is recognized by the mechanisms of absorption as a source of organic nitrogen. As a result, the entire amino acid chelate (chelate + mineral ion) is taken into the cell very rapidly and efficiently.