Young Apple Orchards Research Articles

Growth and productivity of a young apple orchard at different spacing

Planting of new high density apple orchards showed an increasing tendency over the last ten years. Growers use in those orchards mainly dwarfing or semi dwarfing rootstocks. The spacing for those orchards is recommended based on Dutch and German experiences; however, the optimization of orchard planting density as a key factor for successful orchard management should consider the local climate conditions. An experimental orchard was planted in 2000 to investigate the effect of spacing on three dwarfing rootstocks with two apple cultivars `Jonica' and 'Gala Must'. We compared 8 planting densities (1270-3704 tree/ha) and two tree shapes (slender spindle and vertical axis). In this paper the data of the first five years' growth and bearing are presented. After 4 years, the decreasing tree densities caused reduced trunk cross sectional area. Tree density had a significant positive effect on cumulative yield per hectare. From the examined rootstocks, M.9 Burgmer 984 gave the smallest canopy for both cultivars. The trees on M.9 T.337 and on Jork 9 rootstocks have stronger growth. The light interception was measured under the canopy by AccuPAR (Decagon Devices Inc.'s).

Effect of Prohexadione-Calcium Dose Level on Shoot Growth and Fire Blight in Young Apple Trees

Prohexadione-calcium suppresses both shoot growth and fire blight in apple. In young apple orchards, there are conflicting requirements to control fire blight and allow sufficient tree growth for tree establishment. Application of prohexadione-calcium to various cultivars of orchard-grown apple trees ranging in age from newly planted to fifth-leaf trees indicated that fewer high-dose (125 or 250 mg ·liter-1) applications of prohexadione-calcium provided a better balance between fire blight control and growth in young orchards than multiple low-dose (30 or 63 mg·liter-1) applications. The response of early-season shoot growth to prohexadione-calcium treatment dose was linear. However, trees that received high doses of prohexadione-calcium tended to grow more in the latter part of the season, resulting in little or no difference in total seasonal growth between trees that received a few high or multiple low doses of prohexadione-calcium. Enhancement of fire blight resistance by prohexadione-calcium was correlated with shoot growth suppression at the time of inoculation, and the resistance response to prohexadione-calcium treatment dose was linear. Fire blight management strategies that use prohexadione-calcium in young apple orchards are discussed.

BUSINESS AND ECONOMIC EFFECT FROM CULTIVATION OF DENSITY-TREES IN APPLE ORCHARD ON SEEDLING ROOTSTOCKS

During the period 1998 - 2003 in a young apple orchard (1-6 year) with trees of cultivars Florina and Freedom grafted on seedling rootstocks of Winter gold Pearmain and wild apple (standard), planted at 8 m x 7m were cultivated. Other trees called further density-trees from the same cultivars grafted on a clonal rootstock MM 106 (in the rows) and M 9 (between the rows) were grown. It was established that the trees from the two cultivars on seedling rootstocks during the third-fourth year entered almost at the same time into initial fruit bearing period with these trees on MM 106 and M 9. The combination Florina on MM 106 was with the biggest quantity of fruits. The quality of the fruits according to the Bulgarian quality standard was high at all the cultivar-rootstock combination. From the density-trees the yield was average 29250 kg/ha high quality fruits, total production of 17550 lv/ha (1 lv-1 Bulgaria Leva = 0.512 Euro), net income - 6529.5 lv/ha and rate of profitability - 59.29%. The amount of net income (margin of profit) covered the loss of planting and growing of the main trees on seedling rootstocks and the value of the drip irrigation system.

Fertigation of Young Apple Orchards

Experiments conducted since 1986 indicate that multi-nutrient fertigation may be effective in improving early growth and yield of new orchards. However, the early studies did not provide information concerning the contributions of individual nutrient elements to these responses. Experiments were established in 1993 and 1994 to compare effectiveness of alternative sources, rates, and methods of applying K, Zn, and Cu through drip irrigation compared with annual soil surface applications to `McIntosh'/M.9 and `Empire'/M.9 trees. After 3 years, leaf K, cumulative shoot growth, and first crop year yields were increased by application of K. Differences between sources, rates, times, or methods of application generally were not significant when relatively high rates were applied. However, early results from a rate study indicate a significant K source by rate interaction. Soil surface application of K plus drip irrigation appears to be comparable to fertigation in supplying this element. After 2 years, applying EDTA chelates of Zn and Cu through fertigation increased leaf Zn and Cu, respectively, but high rates required are considered to be uneconomical when compared with foliar sprays of these elements.

Ground cover influence on apple aphid, Aphis pomi DeGeer (Homoptera: Aphididae), and its predators in a young apple orchard

Four ground cover treatments were established in a young apple orchard to evaluate their effects on the apple aphid, Aphis pomi DeGeer, and its predators. The treatments were (1) fall rye, Secale cereale, herbicided in spring and summer; (2) white clover, Trifolium repens, and grass mixture; (3) herbicide strips with grassed alleys and (4) woven black plastic strips with grassed alleys. Seasonal tree terminal growth and leaf nitrogen in the clover-grass treatment were significantly lower than in the other three treatments in 1987 and terminal growth was significantly lower than in two of the other treatments in 1988, probably because of ground cover competition with the trees for nitrogen. Trees in the clover-grass treatment had total seasonal aphid and predator densities more than fourfold lower than trees in the other treatments in 1987, aphid and predator densities were more variable and not significantly different among treatments. Few ground cover predators were found except Lygaeidae, which rarely appeared in the trees. Terminals of trees in the non-clover treatments averaged 0.856 m of growth in 1987 despite carrying a mean of over 100 apple aphids per most infested terminal leaf for > 2 months.

Pupation Sites of the Eye-Spotted Bud Moth, Spilonota ocellana and Differences in Degree of Development on Two Apple Varieties in Wisconsin1

Investigations from 1958 through 1962 in a young apple orchard in Door County Wisconsin revealed that the eye-spotted bud moth, Spilonota ocellana (Denis • Schiffermuller), pupated primarily in twig nests which were constructed some distance from the larval feeding sites. Larvae were shown to complete their development sooner on Red Delicious than on Cortland. Bud development was not regarded as a primary contributing factor to these developmental differences.