. Bulletin. Agriculture -- Massachusetts Periodicals; Fertilizers -- Analysis Periodicals. 14 lettuce we find that Botrytis has no connection whatever with the real Drop, but that it is caused by the Sclerotinia. In such cases the disease does not usually appear until just before the crop matures. Its effect is very similar to that of the Botrytis in similar plants. There is this difference, however, that the plant goes off more suddenly and collapses more completely, showing that the fun- gus is more active. Usually but a single night elapses from the time when slight wilting is noticed until
. Bulletin. Agriculture -- Massachusetts Periodicals; Fertilizers -- Analysis Periodicals. 14 lettuce we find that Botrytis has no connection whatever with the real Drop, but that it is caused by the Sclerotinia. In such cases the disease does not usually appear until just before the crop matures. Its effect is very similar to that of the Botrytis in similar plants. There is this difference, however, that the plant goes off more suddenly and collapses more completely, showing that the fun- gus is more active. Usually but a single night elapses from the time when slight wilting is noticed until the whole plant, head and all, lies flat on the ground. (See Fig. 4.) The stem and bases of the leaves are found to be full of the fungous growth, (see Fig. 5.) which appears on the surface as a delicate, white mould. The plant usually rots more completely than when attacked bv Botrvtis and soon the mould spreads to the soil, mak- ing a luxuriant growth upon the sur- face and reaching out to attack neigh- boring plants. If it reaches a leaf, stem, or any part of a plant, it soon spreads over and penetrates it, works down into the stem and produces the disease. This fungus produces no spores as found in Botrytis. On plants in the early stages of decay it consists simply of a mass of fungous threads which reproduce only by direct growth on the plant or soil, being able to live and grow on either. Later, however,- when the affected plant becomes dead and dried up, there may be found on the under side-of the old remains next the soil, very small black granules looking something like the excrements of mice. These are called sckrotia. (See Fig. 6.) They are simply solid masses of the substance of the fungus, which are not so delicate as the mould-like growth, and hence are better able to withstand heat, drying, etc. Sclerotia of larger size are sometimes pro- duced and from these a kind of spore is developed, (See Fig. 7.) but it is very doubt- FiG. 6. Mycelium and sclerotia of the
Size: 1335px × 1871px
Photo credit: © Library Book Collection / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1800, bookdecade1880, bookpublisherslsn, bookyear1888
