September 2011

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!

It's time once again to mention a program that I'm a big believer in. Fall foliar fertilization. Research on foliar application of urea dates back to the 1940’s in California. 1990’s work shows that a foliar spray of urea on peach begins to move into the leaf within two hours, with over 80% of the applied N moving into the leaves within 24 hours. The efficiency of N recovery through a foliar urea application is four-fold greater than through a soil application. (If you're trying to cut back on your annual fertilizer expense this is a program that will get more N in the tree for fewer dollars!) This nitrogen is mobilized and moved into other plant parts such as shoots and buds within one week. Trees move nutrients from the leaves back into the buds and wood prior to leaf drop. It remains there until spring when it is available for early use during cell division (more cells = larger fruit)! Peach fruits have three fairly discrete stages of growth. The first stage (Stage I) lasts from full bloom until about 50 days after bloom. During this time the fruits grow fairly rapidly and growth is primarily due to cell division. Most of the cell division occurs during the first 30 days after bloom, the length of stage I is influenced by temperature. There is an increase in both fruit size and fruit dry weight. During stage I, shoot growth begins but there is too little foliage on the tree to support the growth of the fruit and shoots. Therefore much of the carbohydrates for early fruit and shoot growth come from reserves stored in the tree during the previous season.

Urea is known to enhance the uptake of other micronutrients when sprayed in combination. Adding boron, zinc, iron, manganese or any other element your tree requires will help boost bud strength and tree health. No detrimental effects have been found on winter hardiness, quite the opposite, research has shown that healthy buds with good nutrient reserves are the most winter hardy. Now is a great window of opportunity to put a bit of fuel back in the tank for next year.

It's always good when research and industry adoption validates a program you believe in. The following showed up in my email box a few days ago. It's from Lynn E. Long at Oregon State University

For a number of years now I’ve been mentioning that a fall urea spray may have some benefits to your orchard in the following season. A number of growers from both Oregon and Washington have told me that they have tried this program and are continuing to apply urea at the suggested rate each fall. 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 then photosynthesis in 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.

Every spring I get questions about residual herbicides. It's usually from growers with furrow irrigation and bad weed pressure. Whether you farm with sprinklers or furrow, Fall is the best time to apply next year's residual materials. These materials need incorporation. Making a late fall application greatly increases the odds that a rain or snowfall will set them in place. Plus you get a jump on any spring weed germination. There are a number of materials available, give us a call this fall to take care of next year's weeds!

Pearleaf blister mites are very small, about the same size as rust mites, and cannot be seen without a 14 to 20X hand lens. The body is white, long and slender, striated, and with a few long hairs. Immature forms resemble adults but are smaller. Eggs are spherical and pearly white. Pearleaf blister mites feed under the bud scales during winter and may cause buds to dry and fail to develop in spring. When buds start to grow in spring, mites feed on emerging leaves from greentip through bloom, and on developing fruit. Feeding on fruit results in oval russet spots , usually depressed with a surrounding halo of clear tissue. These spots are 0.25 to 0.50 inch in diameter and frequently run together. When damaged fruit matures, it is often deformed and misshaped. Leaf feeding causes small blisters, 0.125 (3 mm) to 0.25 inch (6 mm) across, which are first red and later turn black. Leaf function can be seriously impaired. Eggs are laid in the blisters and young mites feed inside the blister, they are rarely seen. If your organic (or conventional) pear block suffered this season from pearleaf blister mite (or rust mite), now is a great time (immediately post-harvest) to control them. Both species of mite move under the bud scales at this time of year to overwinter and will be somewhat protected until they re-emerge next spring. Blister mites can reproduce during winter, and all growth stages are found under bud scales. Lime-Sulfur @ 5gal + oil @ 1gal per 100 gallons works well. As always...... good coverage is essential!

The most common timing to apply ground fertilizer has been to make an application in the late fall. Research has shown that uptake and movement into the tree of a dormant application is greatly reduced and subject to winter leaching (recovery of soil-applied N by fruit trees typically ranges from 25-35%, Khemira, 1995). Moreover, a late fall application will not be available till late, (too late) in the spring, past the cell division period when soil temps warm up. A dormant application contributes most toward summer vegetative growth. Consider a different timing. Mid-August to mid-September most terminal growth has ceased, the temps are still warm and the tree is maintaining a high rate of respiration. Fertilizer applied at this time, followed by a light irrigation will quickly be moved up into the tree. It’s then stored, ready for cell division the next spring. The “sweet spot” to aim for is the period when the tree is between it’s summer work and winter sleep. Be cautious about late maturing varieties, they stay active later in the season.

While pest damage is still fresh in your mind, or in the bin, take a moment to think about the following.

Controlling any pest is a matter of:

Using the proper material properly. Choose a material that will do the job. Is resistance an issue? Use a high enough rate to do the job or change classes. Is it a special need and/or timing material? Buffering, spreader, temperature, life stage issues?
Proper timing of your application. All pests have an optimum time to control them. Do you know that timing for each pest in your orchard?
Good coverage. Have you ever walked behind your sprayer and looked at your coverage, looked at all the dry areas in your tree? Water volume is not the issue! I’ve seen dry spots behind a 300 GPA application. According to Kevin Day, University CA farm advisor, “Excessive speed is probably the biggest roadblock to thorough spray coverage”. An air blast sprayer must move the “resident” air from inside the tree before it can replace it with spray laden air. According to Day, “sprayers should never travel over two miles per hour.” I’ll bet that if I were to drive two mph in a race I would lose to every sprayer in the county!

Curious about your spray coverage? Put a bag of Surround in your sprayer and go spray a couple of rows before the leaves fall off. Surround is a white clay material that's very easy to see. It's a quick easy test that will show you how good a job your sprayer is doing….or not!

If you’re having trouble with control, then one of the above is the cause. Don’t assume you know the answer. Work your way down the list.

Here’s to my favorite season……Post-harvest!

Larry 234-3424