Issue link: https://read.dmtmag.com/i/350705
42 AUGUST 2014 Good Fruit Grower www.goodfruit.com KERIAN MACHINES, INC. 1709 Hwy 81 South, P.O. Box 311 Grafton, ND 58237 701-352-0480 • Fax 701-352-3776 sales@kerian.com • www.kerian.com GENTLE: Separates without damaging peaches, apples, mushrooms and fresh tomatoes ACCURATE: Precisely grades grape tomatoes, cherries, nuts, and small berries, maintaining that accuracy for larger products including cantaloupes and pineapple FAST: Thirteen standard models custom- designed to meet your needs sort from 1,000 lb/hr to 100,000 lb/hr SIMPLE: Effective but simple design provides a rugged, low-cost, low-maintenance machine at a high value to our customers. It can even be used in the field! VERSATILE: Specialized rollers allow for the accurate sizing of round products (potatoes, onions, and citrus), long products (carrots, russets, and cucumbers), and irregular products (bell peppers, jalapeños, and garlic) FRUIT AND VEGETABLE KERIAN SIZER There are three kinds of shoots on a peach tree, DeJong explained during the Cornell fruit school, and each responds differently to pruning. In what seems counterintuitive, "You cut what you want to grow," he said. But the cut will result in one of three responses, depending on the kind of wood that is cut. Three kinds of shoots Proleptic shoots bear the crop, and they grow from terminal or lateral buds after dormancy is broken. Syleptic shoots are lateral shoots that grow immediately off the main axis of a vigorous shoot without first form- ing a dormant bud. Epicormic shoots (growers often call these water sprouts) grow where two-year-old (or older) limbs have been pruned or broken, and grow rapidly as long as growing conditions are favorable. Proleptic shoot buds are often entirely preformed (all parts were already present in the dormant bud). Syleptic and epicormic buds do not develop from dormant buds. Proleptic peach shoots rarely form more than 34 nodes in a season, and since new nodes appear every two to three days, all proleptic shoot growth occurs within 90 days of bud break (by mid-June in California). Syleptic and epicormic shoot growth can occur throughout the summer. Shoot structures display relatively consistent distri- butions of blind nodes and nodes with different combi- nations of lateral vegetative and flower buds along their axes. Proleptic shoots tend to have greater proportions of nodes with flower buds than syleptic or epicormic shoots. Another factor that tends to strongly affect tree architecture is apical dominance. As a basic rule, apical dominance tends to depress the growth of shoots below the tip. Thus, if a shoot is not pruned, all new shoots will be shorter than the parent, while cut shoots will be invigorated and grow longer. Shaping a tree The way California growers train peach trees is by tak- ing a tall whip from the nursery and cutting it off at about 20 inches, removing all side branches. The tree's response is to grow many "epicormic shoots"—water sprouts. From these, growers will select, during the dormant period, anywhere from two to six shoots, depending on the style of tree they want to grow. It can be upright like a Perpendicular V, Quad V, Hex V—trees conforming to a "V" shape with two, four, or six main scaffolds —or a more circular open- center vase style. These selected shoots become the basis for scaffolds. During dormancy, they will be headed hard again to continue scaffold development or to develop multiple secondary scaffolds. "In the first year, we want water sprouts to form scaffolds," DeJong said. But after the tree is formed, water sprouts are undesirable, "the bane of a grower's existence," and result in excessive vegetative growth, he said. To prevent water sprouts, growers shift to avoiding heading cuts and doing renewal pruning to stimulate new fruiting shoots and keep enough fruit wood for the next year's crop but avoid heading cuts into older branches. In pruning, DeJong said, growers work with "reit- eration," the tendency of a tree to replace any veg- etative part with a new part like the one that was broken or pruned away. "The strength of the reitera- tion after pruning depends on the type of pruning cut, the amount of growth that was lost, and the timing of the pruning. The growth of epicormic shoots (water sprouts) from preventitious buds is the tree's natural way to rapidly replace large parts of the canopy that is lost." In California, the long growing season generates vigorous growth that growers must battle to keep tree height under control. They use mechanical toppers because they are inexpensive, but this results in more upright water sprout growth. "Recent research combining our new size-controlling rootstocks, the Controller series, with Quad and Hex V systems has resulted in very productive pedestrian orchards with tree heights less than eight feet tall so all hand work can be done from the ground," he said. Peach growers would love to have the choices of rootstocks apple growers enjoy, he said. Managing fruit load "Fruit growth and yield are dependent on two sepa- rate but interdependent sets of processes," DeJong said. "Recent research has resulted in very productive pedestrian orchards." —Dr. Ted DeJong