Effect of zinc applications on the crop of grapefruit trees affected with mottle-leaf
AuthorE. R. Parker
Author AffiliationsE. R. Parker was Assistant Horticulturist in the Experiment Station.
Hilgardia 11(2):35-53. DOI:10.3733/hilg.v11n02p035. December 1937.
Abstract does not appear. First page follows.
The superficial effects of mottle-leaf are readily apparent in the character of the foliage and in the vigor of citrus trees (Fawcett, 1936).4 The reduced size of individual leaves and the retarding of growth causes an obvious decrease in leaf area. According to (Reed and Dufrénoy (1935)), the condition of partial chlorosis involves a reduction in the number of chloroplasts and in the photosynthetic capacity of the leaves.
Such abnormalities might be expected to alter the carbohydrate metabolism of plants and to affect their reproductive activities. In the case of citrus, such an effect might result in a decreased yield and possibly in an effect on the quality of the fruit. In extreme cases of mottle-leaf, these effects are clearly evident on casual inspection. Not only is the crop light, but fruits produced on severely affected branches are small and abnormal; the nature of the abnormalities varies with the species of citrus observed. Where trees are slightly to moderately affected with mottle-leaf, however, it is difficult to tell by casual observation what, if any, influence this disorder has on the amount and quality of the fruit produced.
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Peach tree borer control tests: Fall treatments with soil fumigants and use of trunk sprays evaluated in experimental program during the 1955–56 seasons
Aphid resistance to parathion: Nonphosphate insecticides under study for control of spotted alfalfa aphid where pest develops resstance to parathion
Fungi on spotted alfalfa aphid: Spread of fungi by natural and artificial means is resulting in excellent biological control of aphid in many counties
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California scaly bark disease of citrus: No known cure for infected trees but treatment in early stages of disease can retard its advance into successive stages with their increasing economic loss
Bartlett pears for canning: Ripeness of fruit at time of processing affects color, flavor, aroma, and over-all quality of finished product
Citrus weed control by monuron: Experiments with urea herbicides for weed control in citrus orchards encouraging but use of the chemicals is restricted
Weed control near grass areas: Soil fumigants and contact spray materials included in series of studies on control of weeds in relatively confined areas