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Thinking Ahead - Some cost cutting, pest-controlling and planning points to mull over

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Orchard Nutrition

This year, growers are examining their fertilizer costs more than ever. Balancing your orchard's nutritional requirements against costs, while factoring in the crop load, has become increasingly difficult - nearly impossible, in fact. However, growers realize that this year's crop is already made. Fertilizer inputs must be in place to generate the growth of fruiting spurs for next year's crop.

Certainly, with what appears to be a lighter crop load, nitrogen requirements may be proportionally less. But that consolation may be a bit hollow; oil prices are at virtually all-time highs, which translate into higher fertilizer costs. Unfortunately, your trees don't care. Their requirements for good health remain constant with only some fine-tuning relative to crop load.

The take home message from most advisors is, "If at all possible, maximize inputs: fine tune nitrogen applications; make sure your potash level is adequate; keep micro-nutrient levels appropriate." Of course, apply this advice within the confines of affordability. The bottom line is that it will pay off.

With the 2000 crop apt to be one of the most challenging in recent history, almond growers will have an opportunity to demonstrate the resourcefulness they have exhibited in the past - and, no doubt, will continue to demonstrate in the future.

One of the key elements that growers are relatively quick to remove from their nutrition list is potassium. Certainly, it's expensive, but most progressive growers recognize it's also cost effective. Potassium is critical for good fruitwood development. It also contributes to better overall health of the tree and, generally, orchards with optimum potash levels have more consistent bud sets and crops. The tree mines a lot of this important element from the soil. Unfortunately, fertilization programs do not always replace what was absorbed or apply potassium in the amount needed by the crop.

A grower may choose from several methods of applying potash.

  • Potassium chloride - the lowest-cost method, but chlorine toxicity can result if the material doesn't leach and is left in the root zone.
  • Potassium sulfate - safe, stable, a little more costly and the material is not very soluble.
  • Potassium nitrate - extremely soluble, immediately available to the trees, but fairly expensive
  • Liquid Potash - fairly safe, stable, good maintenance source, somewhat more expensive on a per-unit basis.
  • Foliar Potassium - can relieve symptoms temporarily.

Variety Selections

Each year, during the spring, growers begin to make variety selections for the following year's plantings. Nurseries generally provide appropriate categories of varieties that fit individual grower's situations. However, it is important to recognize that not all varieties are compatible with certain classes from the bloom, harvest, and marketing standpoints.

Marketing and harvest compatibility are key components in the decision process, and are especially important to keep in mind when replanting in established orchards and planning close plantings. Make sure the varieties you select do not present the potential for mixing two classes of almonds. This could be a costly mistake. It takes only l0 percent of an incompatible variety to change the grade.

Here's a checklist of considerations that may influence your choices.

  1. Make sure that the selection will be compatible with other classes from a harvest standpoint. Some varieties will harvest so closely to another class that it may be impossible to separate them. This is particularly critical in close planting.
  2. Not all pollinators follow classic literature when they bloom.
  3. Check to see which marketing category each pollinator fits into.
  4. Make sure the pollinator is a desirable nut from a marketing standpoint.
  5. If it's a new nut - research it thoroughly.
  6. Finally - please - check with your Blue Diamond® Field Supervisor. He will be glad to provide objective input to help you and your nurseryman make a decision that will best suit your specific situation.

Ground Squirrels

In much of the almond growing area throughout state, control of the California ground squirrel is not a high priority. However, if you happen to be one of the lucky growers who provide a homey habitat for these furry "friend," your tolerance for the beasts is likely limited. Ground squirrels are the most destructive vertebrate pests found in almond orchards. They are energetic diggers, creating large mounds and burrows that can be extremely bothersome, especially at harvest. They often feed on bark, buds and blossoms, but of greater concern, they can practically strip a mature tree of its crop.

Squirrels are most active and reproduce in the spring. Adults will forage then and again in the fall. The best control methods in the spring include fumigation and trapping; in summer and fall try baiting. Here are some tips:

  1. BAIT STATIONS can work well for ground squirrels. However, bait stations must provide a steady supply from which the squirrel can regularly feed, until the material has had time to take effect. Since the bait is an anticoagulant, its effects are cumulative. It is important to make sure that the bait station never runs out of bait so that the squirrels do not change their feeding habits, because, if a squirrel does not feed for around 48 hours, the level of toxicity within the animal is greatly diluted and the material loses a great deal of its effect. The toxic level in the pest must then be built up again. Another important point is that acceptance is greatly reduced when the material is not fresh or has become moldy or spoiled.
  2. FUMIGATION works very well when all burrow openings can be sealed and there is sufficient soil moisture to prevent the escape of toxic gas through cracked or dry soil. This method is generally most effective in late spring or fall when the soil is still fairly moist. The procedure is relatively simple:
    • Seal all untreated openings.
    • Place appropriate amount of tablets in burrow.
    • Plug treated hole with newspaper wad.
    • Cover treated burrow with soil.
  3. TRAPS can provide a fairly safe method of control, particularly where it is imprudent to use toxic materials. Unfortunately, traps require constant monitoring and control is most effective at a lower threshold.

Peach Twig Borer (PTB)

Historically, most of the serious reject damage in a given crop was caused by navel orange worm (NOW). The Peach Twig Borer (PTB), on the other hand, may not be a serious pest statewide, but if you happen to be in an area where it is prevalent, it is of great concern. Fortunately, it is easy to trap and monitor, and identify. The pest is about 3/8 inch long, has a black head, and a chocolate-brown body with white stripes between each body segment. Where infestations occur, you will find flagging in the young growing shoot. About the only other flagging pest the PTB could be confused with is the Oriental Fruit Moth larva, but it has a cream-colored body.

A little bit about the biology of PTB: There are usually four generations of PTB. Over-wintering larvae emerge and develop in green spring shoots. Then they emerge. The first generation of moths lays eggs from mid-April through May, which is when many growers target their first in-season sprays (other than b.T. sprays) to knock down the first brood of larvae when they emerge. The second brood's larvae emerge from mid-Jun through July to feed on green tissue and nuts. There can be two more broods, one of which can still feed on exposed almonds in August.

As you can see, PTB can be prolific. Nevertheless, many growers have recently decided not to apply a dormant spray. Arguments can be made pro or con on that issue, but the fact remains that a well-placed (good coverage) dormant spray has great efficacy in controlling PTB. If numerous growers are not targeting PTB but are treating specifically for NOW, we could be in for a rise in PTB incidence. If you suspect or have identified PTB to be the predominant cause of rejects in your recent deliveries, a well timed spring spray can be an effective tool to control the pest before it builds up.