. Cirtus fruits under irragation. Citrus fruits; Fruit-culture. Fig. 8 often found beyond the range of the black scale. The red scale gives off no honeydew, differing from the black scale in this respect. The red scales may injure the tree in several ways. It may be that the insects check the growth of the tree by sucking the sap or it may be that the insects have the same effect on the citrus trees that the San Jose scale has on the apple. The San Jose scale on the apple and other deciduous fruits produces a pink discoloration. This discoloration is spoken of as a toxic effect. It may be that
. Cirtus fruits under irragation. Citrus fruits; Fruit-culture. Fig. 8 often found beyond the range of the black scale. The red scale gives off no honeydew, differing from the black scale in this respect. The red scales may injure the tree in several ways. It may be that the insects check the growth of the tree by sucking the sap or it may be that the insects have the same effect on the citrus trees that the San Jose scale has on the apple. The San Jose scale on the apple and other deciduous fruits produces a pink discoloration. This discoloration is spoken of as a toxic effect. It may be that the red scale exerts the same influence on the citrus fruits without producing any discoloration on the trees or fruit. It is true that when the scale feeds on the leaves, a yellow spot results at the point § 24 CITRUS FRUITS UNDER IRRIGATION 31 where the leaf is injured, but this is due to the loss of chlorophyll n the leaf rather than to any toxic effect on the leaf. Again, t might be said that interference with the exchange of gase by the scales covering the stomates of the leaves or a combina- tion of all these causes has some effect on checking the growth red ; f ?f ''^ "^'"^^ ^^ ^^^ '"^^-^y^ i'- tru^ that red scales infest all parts of the tree and are much more virulent. Fig. 9 mthor effects on the tree than any other scales on citrus trees. A tree badly infested will be severely injured in a comparatively short ime. Often trees are killed in 2 or 3 years by a bad infestation of the red scale. In addition to the injury to the tree, the fruit is made less desirable by the presence of scales on Its surface. In Fig. 8 old and young red scales on a section of an orange are shown magnified about ten times, and m i<ig. «) the scales on twig, leaves, and fruit of the lemon are. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations
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Keywords: ., bookcentury1900, booksubjectcitrusfruits, booksubjectfruitcultur
