Premature fruit ripening and significant decrease in fruit quality is characteristic for trees in water-saturated soils. The yellowing of leaves generally starts on the lower part of the tree on the inside of the crown and then moves outward. Tree roots in waterlogged soils stop growing, minerals are not absorbed, leaves turn yellow and remain small, and finally roots begin to die. Excess soil moisture excludes oxygen from the soil, resulting in severe injury to the root system. Too Much WaterĮxcess water (water stress or flooding) is just as damaging as not enough water (figs. Moreover, dwarfing stocks bear more fruit per leaf area than standard-sized or semi-dwarfing stocks, and the presence of the relatively large number of fruit significantly increases transpirational water loss under such stress conditions. Young or newly planted trees and trees on dwarf rootstocks, such as M.27 or M.9, with shallow root zones are more sensitive to drought stress. Large, established trees with deep roots and trees on standard-sized or semi-dwarfing rootstocks, such as M.26 and MM.111, tolerate short periods of drought. When leaves are scorched, their edges dry out, and the leaves turn brown.ĭue to considerable differences in root growth, rootstocks have great influence on drought tolerance of apple trees. When drought stress and heat stress coincide, scorching of the leaves occurs in addition to the symptoms mentioned previously. Often, drought stress is associated with heat stress during the hot summer months. Drought stress causes wilting, yellowing of the leaves, advanced leaf fall, and premature fruit ripening or fruit drop. When water demand of a fruit tree is higher than supply, drought stress occurs. Apples may also be stored in inert gases or in controlled atmospheres.One of the most common causes of tree decline or death is imbalance of water demand and supply. For long holding, temperatures only slightly above the freezing point of the fruit are generally desirable. Apple varieties that ripen during late summer are generally of poor quality for storage, while those that ripen in late autumn may be stored for as long as one year. In the United States, popular dessert varieties include the Honeycrisp, Red Delicious, Gala, Granny Smith, and Golden Delicious. Many varieties are relatively high in sugar, only mildly acidic, and very low in tannin. Apple varieties fall into three broad classes: (1) cider varieties, (2) cooking varieties, and (3) dessert varieties, which differ widely but tend to emphasize colour, size, aroma, smoothness, and perhaps crispness and tang. When harvested, apples are usually roundish, 5–10 cm (2–4 inches) in diameter, and some shade of red, green, or yellow in colour they vary in size, shape, and acidity depending on the variety, of which there are thousands. The apple itself is a pome (fleshy) fruit, in which the ripened ovary and surrounding tissue both become fleshy and edible.
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