. Fungous diseases of plants : with chapters on physiology, culture methods and technique . Fungi in agriculture. 146 FUNGOUS DISEASES OF PLANTS. fungus penetrates the rind and other fibrous portions of the lemon to a considerable extent; it is much branched, irregular in diameter, and extensive. Upon the lemon, as a rule, no form of spore is produced, but there is developed frequently a con- spicuous aerial growth due to the emergence of many mycelial branches. In some cases these are produced in more or less tuber- culate masses. Conidia and sporangia appear under favorable conditions. In mo
. Fungous diseases of plants : with chapters on physiology, culture methods and technique . Fungi in agriculture. 146 FUNGOUS DISEASES OF PLANTS. fungus penetrates the rind and other fibrous portions of the lemon to a considerable extent; it is much branched, irregular in diameter, and extensive. Upon the lemon, as a rule, no form of spore is produced, but there is developed frequently a con- spicuous aerial growth due to the emergence of many mycelial branches. In some cases these are produced in more or less tuber- culate masses. Conidia and sporangia appear under favorable conditions. In moist soil near affected fruit the sporangia are developed abundantly upon a fine much-branched my- celium (Fig. 47). The sporangia measure 20—60 X 30—90yu. (averaging 35x50^). They are lemon-shaped, or subspherical with pronounced apical protuberance. In water Fig. 47. Sporangia of germination is effected by means of a vari- Pythiacystis. (After aWe number of Z00Sp0res, often about thirty, each biciliate with long cilia (Fig. 48). Control. Ordinarily the fungus does not produce any spore stage upon the surface of the lemon. On moist soil, however, it produces sporangia and sometimes conidia. The infection of the fruit usually takes place in the orchards, and also subsequently by direct contact and also by the operation of washing. It has been found, for instance, that if uninfected lemons are dipped in water in which diseased ones have been washed, infection will in time result on the healthy fruit. In fact, the ordinary wash water may itself contain a large number of germs of this fungus and it may also live more or less permanently in the machine used for wash- ing such fruit. The remedy, therefore, for cystis. (After ) such conditions is very simple and merely consists in treating the water used for washing purposes with some aseptic or toxic agent. The most practicable method which has been devised con- sists in using copper sulfate, formalin, or potassium perma
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Keywords: ., bookauthorduggarbe, bookcentury1900, bookdecade1900, bookyear1909
