วันอาทิตย์ที่ 21 กันยายน พ.ศ. 2551

How to Grow Durians # 3

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Management: Following planting, young durian trees should be provided with temporary shade and complete wind protection for the first year, as in a shadecloth nursery structure or equivalent. The structure of the young trees and their leaves is such that strong winds can twist the leaves right off, a setback from which they are unlikely to ever fully recover.Proper pruning of the durian tree is said to be important to obtain a tree form that encourages early flowering and good yields. The pruning system commonly used in Southeast Asia includes:formative pruning resulting in a main leader; after about age 2 or 3 the interior is thinned out, removing all thin or dead branches and water shoots encouraging early branching to encourage early bearing
topping to maintain a manageable tree height as the tree grows oldergeneral maintenance pruning contributing to a healthy and productive tree, removing dead, broken or diseased branches and water shoots, and allowing free circulation of air and plenty of sunlight throughout the canopy
In Southeast Asia, cut surfaces are routinely treated with a fungicide and bitumastic compound (use an organic equivalent).
Durian growers in Thailand are often advised to keep the area under the tree and drip line area free of weeds, manure, and mulch, primarily so as to not create a microclimate suitable for the thriving of Phythophora palmivora disease. (As previously mentioned, it is not clear if this is necessary or advisable in using strictly organic methods. Durian trees are otherwise benefited from manure and mulch, like many other trees). Likewise, for the same purpose, the trunk of the tree is kept free of any water shoots and weak branches up to a height of about 1 m [3 feet] above the ground. However, tropical legume cover crops between trees, such as perennial peanut, are recommended.
Durian trees are surface feeders, and if any weeding is necessary (with a cover crop like perennial peanut, there shouldn’t be much), care should be taken to prevent damage to the roots.
Durian trees remove a relatively low amount of nutrients from the soil. However, like many other fruit trees, it is a good idea to at least quarterly topdress the soil under the tree with a mix of organic fertilizers (preferably particularly rich in nitrogen and potassium) during the first five years. (Animal manures are favored in most places for this purpose, but not in Thailand, where chemical fertilizers are widely used in commercial production). T.S. Chang of Bao Sheng Durian Farm recommends placing topdressed fertilizer just beyond the edge of the root zone so that the trees’ roots will chase after it and expand their reach in the process. The times a few months before flowering, during fruit development, and after harvesting are favored for fertilizing durian trees throughout Southeast Asia.


Water: In Asia, areas with a dry season longer than 3 months are regarded as marginal for durian, unless adequately irrigated, in which case there is no problem. Micro-sprinkler or drip irrigation can be used. Durian trees are as incapable of withstanding any standing water around their trunks as papayas; they will simply die. In low-lying rainy areas, it may be advisable to construct surface drainage systems to prevent that possibility from ever occurring, or to plant only on sloped land, as is done in many areas of Southeast Asia.


The times most critical for water for the durian tree are during flowering and fruiting. In equatorial regions, it needs at least three to four weeks of dry weather without rain to produce flowers to fill all branches. (Farther from the equator as in Hawai`i, this may not hold true, and day length and temperature may be the primary factors in inducing flowering). Like mango trees, heavy rains and wind during flowering can knock off many of the blossoms, decreasing or even eliminating fruit production that season. When blossoms are forming, water is sometimes deliberately withheld to enhance flowering. To maximize flower and fruit production, after allowing a 3 to 4 week dry period, growers in Malaysia then begin applying irrigation.


Topdressing the trees with organic fertilizer just before flowering also increases production. Various cultivars may have their own unique responses to dry weather and irrigation; for exam-ple, the common Malaysian cultivar D24 is sensitive even to short dry spells; the common Thai variety Chanee tends to drop flowers if watered as much as other varieties. An unseasonal drought may provoke durian trees to an out-of-season round of flowering and fruiting.Pests: As with any plant or tree, the best way to minimize damage of durian trees or fruit by pests or disease is to keep the soil and tree as maximumly healthy as possible using modern organic methods.

Except for usually light damage by local fruit borers, beetles, and leaf cutters in some areas, the tree and fruit tend to be relatively free of insect pests. Phytophthora palmivora is a dreaded fungus disease of durian trees in Southeast Asia. The organism is a primary parasite of durian roots. Symptoms are canker development on the trunk at or just above ground level, and an oozing of brownish-red gum at the collar of the tree, up the trunk and down to the roots, which can result in complete girdling and subsequent death of the tree. The organism gains access to the interior tissues of the tree suitable for its growth through natural or pruning wounds, thus hygienic pruning and using (natural) fungicides are very important to guard against infestation. Grafted trees are said to be particularly susceptible due to cracks that often form in the tree structure due to inherent grafting weaknesses. In Thailand, as previously noted, steps are taken to eliminate a moist microclimate at the base of the tree which might support the growth of P. palmivora, such as not using animal manures or mulch, and removing any branches starting to grow below about 1 m [3 feet] height. Growth of P. palmivora in Southeast Asia is also controlled by using cultivars known to be resistant.


More cultivation information: click here to view the Durian chapter (19 pages) from The Production of Economic Fruits in South-East Asia by Othman Yaacob and Suranant Subhadrabandhu (Oxford University Press, New York, 1995).
CREDIT BY :http://www.durianpalace.com


SEE PAGE DURIAN #1
SEE PAGE DURIAN #2

SEE PAGE DURIAN #4

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