Tree onion

The herbs chives and garlic chives also belong to this family, as does the perennial Egyptian or tree onion, which produces aerial bulbs in place of flowers these may sprout and grow in situ. Flowers of leeks and garlic may also produce tiny bulbs in place of seed. 

Tree onion (AHium cepa Proliferum Group)... 

Bul blets.—Small above ground bulbs, as in the tree onions. 

FIGURE L Chromosome complements in root tips A) the horse bean, Vida faba B) the tree onion, Allium proliferum (C) the common onion, Allium cepa. Acetic alcohol, Feulgen squash. 

In comparison with seeds of F. faba, bulbs of A. cepa have the disadvantage of being more difficult to store (humidity and temperature are more critical) and they also require more space because of their greater bulk. These disadvantages and some of the others mentioned above are largely avoided when bulbs of the tree onion are used. 

The tree onion, also called the top onion or the Egyptian onion, does not produce seeds but is propagated by top-sets of a large number of bulbs... 

The tree onion is winter hardy. Thus, in Sweden it can easily winter in the field as far north as Uppsala. Since a larger number of bulbils can be obtained from each plant, the material needed for a year of experimental work may be grown in a small garden. For more information about the botany and cultivation of the tree onion, the reader is referred to the book Onions and Their Allies by Jones and Mann (1963). 

Since the tree onion is propagated vegetatively, the material is genetically uniform. The root-tip chromosomes of the tree onion are shown in Fig. IB. Their number is the same as that of A, cepa, viz., 16, and they are of about the same size as the cepa chromosomes. However, the proliferum chromosomes are easier to identify than those of A. cepa. In proliferum the chromosomes do not form identical pairs. Thus, the root-tip cells of A. proliferum have only one satellite chromosome, which has a larger satellite and a shorter short arm than the pair of satellite chromosomes in A. cepa. (This satellite chromosome is, in fact, very similar to those of A. fistulosum, which supports the suggestion that the tree onion is more closely related to A. fistulosum than to A. cepa.)... 

Sulfur has long been known for its properties as a pesticide and a curative agent. Homer spoke of the pest-averting sulfur as far back as 800—1000 BC, Hippocrates (400 Bc) considered sulfur sa an antidote against plague, and Dioscorides (100 ad) used sulfur ointment in dermatology (244). In 1803, the use of a lime—sulfur protective treatment for fmit trees was reported, and in 1850 sulfur dust was used to protect foHage (245). In 1891 sulfur dust was used on soil to control onion smut (246). 

Diphenyl ethers are both systemic and contact herbicides and are used for the selective control of annual broad-leaved weeds and grasses in a variety of crops (such as soybeans, maize, rice, wheat, barley, peanuts, cotton, onions and ornamental trees) under different application scenarios. This class of herbicides contains a diphenyl ether moiety as the core substructure. Acifluorfen, bifnox, chlomethoxyfen, chlorni-trofen, fluoroglycofen-ethyl and fomesafen, etc., are representative compounds of the diphenyl ether herbicides (Figure 1). 

Refined oils of the Stoddard solvent type, safe and effective for handling carrot crops, were developed after a relatively short period of research. Their use spread to celery, parsnips, parsley, and anise. Foresters, finding that conifer seedlings were tolerant to the refined oils, sprayed forest tree nurseries. Research proved that a somewhat less toxic oil could be used on flax and onions. The use of refined selective spray oils found a definite place in the agriculture of our country. 

Catechol occurs naturally in fruits and vegetables such as onions, apples and crude beet sugar, and in trees such as pine, oak and willow. Catechol may be released to the environment during its manufacture and use. It has been detected at low levels in ambient and urban air, groundwater, drinking-water and soil samples. It has been foimd in wastewaters from coal conversion, coal-tar chemical production and bituminous shale (United States National Library of Medicine, 1997). It is present in cigarette smoke at 100-360 gg per cigarette (lARC, 1986). 

II, 2-dihydro-3.6-pyridazinedione) is used to inhibit the growth of certain food commodities when in storage, including onion and potato. Maleic-hydra/ide is also used to promote dormancy in citrus trees as well as increasing protection from Irosi. 

Uses herbicides/insecticides pre- or post-emergence control of broadleaf weeds in cereals, maize, lucerne, clover, trefoil, grass leys, potatoes, peas, onions, garlics, peas, leeks, soya beans, orchards, groundnuts, strawberries, vineyards and other crops for control of strawberry runners and raspberry suckers and overwintering forms of insect pests on fruit trees also used as a desiccant for leguminous seed crops destruction of potato haulms as a pre-harvest hop defoliant, etc. 

Chemical Name 3-(4-chlorophenyl)-l-methoxy-l-methylurea Af,-(4-chlorophenyl)-Ar-methoxy-Ar-methylurea Uses herbicide for pre- or post-emergence control of annual broadleaf weeds and annual grasses in asparagus, berry fruit, cereals, maize, field beans, vines, leeks, onions, potatoes, herbs, lucerne, flowers, ornamental shrubs and trees, etc. 

Synonym Albrass, Bexton, CIPA, CP 31393, Niticid, Propachlore, Prolex, Ramrod, Satecid Chemical Name 2-chloro-AL(l-methylethyl)-Af-phenylacetamide 2-chloro-V-isopropyl-acetanilide Uses selective pre-emergence herbicide to control most annual grasses and some broadleaf weeds in brassicas, corn, cotton, flax, leeks, maize, milo, onions, peas, roses, ornamental trees and shrubs, soybeans, and sugar cane. 

The resistance to ozone-induced tipburn in onions mentioned earlier is being incorporated into commercial onion varieties primarily for the Midwest at the University of Wisconsin (12). In a program at the University of Tennessee, dark green vigorous trees have been selected in stands of eastern white pine in which most trees have died because of sensitivity to ozone, S02, and automobile exhaust constituents. Crosses have been made to determine the genetics of resistance, and a formal breeding orchard of resistant trees has been established (13). 

Control Spray dormant oil on fruit trees encourage native predators, such as pirate bugs, lacewings, and lady beetles for onion or western flower thrips, release the predatory mite Amhlyseius cucumeris or minute pirate bugs (Oriiis tristicolor) hang blue or yellow sticky traps to catch adults spray insecticidal soap, pyrethrin, or neem as a last resort, dust undersides of leaves with diatomaceous earth. 

Prevention and Control Sulfur dioxide is an air pollutant, primarily a result of industrial processes. Where these pollutants are a problem, grow tolerant trees such as ginkgos, junipers, sycamores, and arborvitae. Vegetables that tolerate sulfur dioxide include cucumbers, corn, and onions. 

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