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Abnormalities of non parsitaire or unknown cause The first microscopically small symptoms consist of damaged spots on the stamens, which will develop into rot over a period of time (stamen necrosis). Usually the entire flower bud will become black with rotting (flower necrosis), with which especially the upper side of the adjoining upper leaf is grass green and often has little brown spots. With the most serious cases of bud necrosis the leafs of the foliage will be wasted away as well, starting with the upper leaf, with which even the entire head sprout can be lost (sprout necrosis) [266]. There will be spiky leaves or flowering sprouts (stick plants) coming from the offset. Plants with bud necrosis usually have good rooting. Depending on the measure at which the sprout has been affected, more or less serious abnormalities will be diagnosed after the plant comes up. In the case of stamen necrosis the plant will grow normally. Flower necrosis can be recognised by the black remains of the flower at the top of the stem, of which the upper internode will not grow above the leaf. The foliage leafs will then be a bright green and a little shiny. At first bulb mites will damage the stamens, after which fungi and bacteria will cause rotting. Under good –ethylene-free – storage conditions, mites cannot reach the sprout and flower bud. Under the influence of ethylene however, a space will develop between the bulb scales earlier than usual, and slimmer and shorter foliage leafs will appear, that cannot completely surround the young flower bud at the time of its completion (G stage); because of this the flower bud has become accessible to the mites. They will feed on the stamens, which will subsequently start rotting. Open sprouts will develop before September because of exposure to ethylene for 1 to 2 weeks at a temperature of at least 17ºC. Below 17ºC the development of open sprouts and the activity of the mites will quickly decrease. There is a large difference in sensitivity to bud necrosis between the many cultivars. With certain cultivars like ‘Thule’, ‘Red Champion’, ‘Erna Lindgren’ and other parrot tulips, open sprouts can also develop without exposure to ethylene as a result of storage at a high temperature during the period before the G-stage.Diseases: Bud Necrosis 
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