. Cottony rot of lemons in California. ossoms of apricots,1 attacking them while still enclosed by thecalyx or outer cup of the blossom. The leaves of lemons are sometimes attacked while they are at-tached to the tree. There is not, however, any marked defoliation,probably only the older and weaker leaves being susceptible. Cover-Crop Infection.—There is no question but what the cottonyrot decay has increased with the increased growing of cover same fungus not only occurs as a rot of the lemon, but is alsocapable of becoming a parasite on certain cover crops, vetch being byfar the mo
. Cottony rot of lemons in California. ossoms of apricots,1 attacking them while still enclosed by thecalyx or outer cup of the blossom. The leaves of lemons are sometimes attacked while they are at-tached to the tree. There is not, however, any marked defoliation,probably only the older and weaker leaves being susceptible. Cover-Crop Infection.—There is no question but what the cottonyrot decay has increased with the increased growing of cover same fungus not only occurs as a rot of the lemon, but is alsocapable of becoming a parasite on certain cover crops, vetch being byfar the most common host. While the fungus is common on vetch, theinjury it does to the crop as a whole is negligible. The dense growthof vetch affords a suitable place for the fungus to grow as a saprophyteor weak parasite on the weaker shaded portion of the vines. (Fig. 10)Under the vetch cover crop the sclerotia are produced in large numbers i Bulletin No. 218, California Experiment Station, p. 1097. COTTONY ROT OF LEMONS IN CALIFORNIA 243. Fig. 5.—Cottony rot affecting lemons by contact in a packing-house tray. 244 UNIVERSITY OF CALIFORNIA—EXPERIMENT STATION and can be found in infested orchards with little searching. The moreupright cover crops, like Melilotus indica, would probably be less favor-able for the development of the fungus, although this phase of thesubject has not been thoroughly investigated. The spore stage hasbeen found in orchards having a straw mulch, but never in so largenumbers as with vetch (Fig. 11). There is no question of a definiterelationship existing between this fungus and some of the commoncover crops in use, but this apparently should not in any way dis-courage their use. The control of the fungus must be sought for inother ways than through discontinuing the use of green-manure crops. CAUSE OF DISEASE The decay, as already suggested, is due to a fungus belonging tothe genus Sclerotinia. From the preliminary study thus far made, itis believed that
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