by Bob Purvis
During the past sixteen years, I have planted a few hundred fruit trees and recently watched the planting of several thousand at our Richland fruit ranch. Here are some observations I would like to pass on to Alaska Pioneer Fruit growers members who plan to plant trees in 1997.
The first comment is that good preparation of the planting site pays off handsomely down the road. The first thing to consider is sun exposure—for best fruitfulness, a site should have at least six hours of direct sun per day. The second is to evaluate the condition of the soil. The testing laboratories I am familiar with here in the Pacific Northwest charge about $38-43 to do a complete soil analysis, which will tell you the pH and amount of nitrogen, phosphorus, potassium, calcium, sulfur, magnesium, organic matter, soluble salts, and micronutrients such as boron and zinc in the soil. As 1 think back on my experiences with apple, trees in Alaska, I recall that the one subject that we were almost totally ignorant of was soil-fertility management. In 1985, my mentor Dan Whitney came up to visit and took a leaf sample off my apple trees. This showed the trees to have excessive amounts of phosphorus and potassium, marginal amounts of calcium and magnesium, and low levels of zinc and especially boron. These last two micronutrients are especially important for developing healthy leaf and flower buds. Boron is critical for the meristematic tissues in fruit trees—flower buds, shoot tips, and root tips—where active cell division is occurring. It is generally at marginal to deficient levels in central Washington unless supplementary applications are made. This element is less available when the soil pH is somewhat above or well below neutral (pH of 7.0).
Soil drainage is another issue which is oftentimes neglected. Planting trees on mounds will help considerably; also consider putting a few inches of fine gravel or coarse sand in the bottom of the hole and making the bottom slant, so that tree roots are not continually wet.
If you plan to order bare-root trees the following spring, consider doing this: before the soil freezes, take some of the soil from the future planting hole and keep it in a 5-gallon pot until early spring. When your trees arrive, keep them cool while the pot thaws and then plant them in the soil in the pot until it is warm enough to plant them outside. This could be very critical is your trees are breaking dormancy when they arrive.
With regard to amending the soil compost is best for lightening heavy clays of improving sandy soils. Go easy on mixing composted steer, rabbit, or chicken manure with the soil—no more than 5% by volume. Manures seem to be a two-edged sword: they supply a little N, P, and K and improve the soil’s moisture-holding and nutrient-holding capacity, but if you overdo it, the slow release of the nitrogen can delay the tree’s going dormant in the fall, which seems to be one of the main causes of trees dying in the winter in Alaska based on what I’ve seen.
Most members of the APFG probably know that mid- to late May (or in a warm year, early to mid-May) is a good time to plant dormant nursery stock. Once the trees are in the ground, keeping the soil adequately moist is critical in the first year and very important after that—May tends to be one of the drier months of the year in Anchorage. Here in Washington under the hottest of conditions, evapotranspiration from newly planted apple orchard blocks is about 0.21” of soil water per day. In mature orchards, this rises to 0.28-0.32” per day. Extrapolating from what the rate is here in May or September, I would estimate that in July, you should plan on mature trees extracting perhaps 0.20” of moisture per day from the soil in Anchorage, new trees, 0.15”.
In establishing new orchard blocks, we like to water every 2-3 days, supplying about 0.40-0.60” of water at each irrigation. The main objective is to keep the soil moisture levels from wide fluctuations. If the soil becomes too dry, the trees will set terminal buds. The tendency for Washington fruit growers is to over-irrigate in the spring and under-irrigate in midsummer. In heavier soils, you should not apply more than 0.10-0.15” per hour, otherwise there will be cither run-off or standing water in the soil. (Most of the Chiawana Orchards blocks have irrigation systems designed to supply 0.10” per hour,) Here in Selah, my microsprinkler system applies 0.16” per hour. Our loam soils accept this without runoff or standing water. You can use a tuna can or juice can to measure the amount of water being applied.
In the planting of the trees, it is essential that the roots do not dry out before planting. If the roots and packaging material look dry when your shipment arrives, put them in a bucket of lukewarm water with a little Up-Start, Vita-Start, or other transplant solution added for 12 hours or so (but never over 24) before planting. Prune off or shorten roots that circle or cross one another — this is the only opportunity you will have to train the root system.
Once the trees are in the ground, provide support to the trees. Do not lie the trees tightly to a stake, but set out two stakes opposite each other and about one foot out from the trunk. That way, light can reach ail the buds on the tree, and all will have at least some chance to put out side branches (laterals). Whipping around in the wind, an unstaked tree will break off newly forming root hairs on the root crown, and this will delay its getting established in the soil. Experiments done by the WSU Horticulture Department in Pullman, plus grower experience on the Naches Heights showed that staked or supported trees typically would have 30% more shoot growth the first year and 35-40% more flowers and fruit in the second year, than those left unstaked.
Many of the containerized trees sold by nurseries in Alaska had several upright branches competing to be central leaders. If the crotch angles on them are extremely narrow (less than 30 degrees), the best thing would be to make a bench cut an inch or so from the trunk at planting. A little later in either the first or maybe in the second growing season, dormant buds on the stub will put out shoots that either will have good crotch angles or can be trained.
If the trees you get are small (less than 3’ tall), try to get them to grow to at least 4’ before promoting branching, by cutting off the growing tip. In view of the danger of snow breaking off limbs as it forms crusts, do not allow the tree to form permanent branches less than 3’ above the ground.
I strongly advocate putting limb spreaders in the crotches of branches. Most of you know that a limb growing out at a 45 degree or flatter angle will fruit earlier and heavier than those that are growing vertically. Also, the crotches will be stronger and less likely to break.
Unless you have an exceptionally heavy or vigorous tree, it is probably best not to allow it to fruit the first year it is planted — or if you must, no more than one apple! A small crop the next year (its second growing season in Alaska) should be permissible, but follow the rule of having at least 40 leaves for each piece of fruit Consider thinning the fruit when it is about the size of a dime, to no more than one fruit per spur.
With regard to fertilizing fruit trees, the key here is to use quick-acting forms of fertilizer, Miracle-Gro being a good example, or possibly calcium nitrate. The latter is about 16% by weight. In the first year, a few waterings with perhaps a gallon of Miracle-Gro (15-30-15) should be enough to get your tree growing well. Using calcium nitrate, the best time would be early June, and half a pound of the material spread around the trunk of the tree should be quite sufficient. It would also be okay to spray your trees with Miracle-Gro in early August. Here in Washington State, researchers have found that if nitrogen is applied to trees in small quantities (20-25 lbs/acre of actual N to the soil, or 4-5 lbs/acre of actual N as foliar urea) in early to mid-August, it does note promote additional shoot growth but goes into storage reserves and actually promotes better flowering the following spring.
One of the key cultural practices to promoting good tree growth is to keep the area around the tree free of weeds. In reviewing slides I had taken of Alaska fruit trees, Dan Whitney observed that most of them had a lot of weeds or grass growing around them. This is especially critical of newly-planted trees; mature trees will cast some shade and thereby discourage weed growth.
To summarize, analyzing and preparing the soil the previous year will help greatly in establishing your trees. Find out what the soil is lacking and then supply it; determine its faults and try to correct them. Be sure that broken or circling roots are pruned back before planting the tree. Give the tree support, spread the branches, and give it water in small but frequent doses. Try to do as little pruning as possible the first year, and keep the first whorl of branches above the snow line. Supply fertilizer in small quantities, early, of substances that act quickly.
After you have read this article, let the editor know if there are other topics related to cultural practices that you would like an article written on, and I will see what I can do.
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