OCR Text |
Show u DRY ROT OF CORN. r. The group of diseases of corn known under the general name of dry rot has become if sufficient economic importance during the past four or five years to cause general concern among farmers in corn growing re 1 gions. In 1906, the year in which there was the greatest amount of dry rorf so far as any records have been I made, the loss was 4..s-pcr cent of the 1 entire crop in the one state of U'i- nois. This represents a loss of over 15,000,000 'bushels, having a value of j more than $5,000,000. The loss in i 1907 was less than a per cent of the crop or about $2,000,000. The name dry rot-is derived from the way the ears arc affected in the fields. In general the husks tend to turn prematurely- yellow to soot, and the ear becomes partially or wholly shrive'led and much decreased decreas-ed in weight. Sometimes the cas remain upright with the husks1 closely close-ly adhering to them. In other cases the shanks arc weakened and the affected af-fected ears hang limp' from their attachment, at-tachment, or the diseased aondition may not be detected until the husk is removed, There are several different kinds of !dry rot, due to different causes. The most common and that which during the past two seasons caused about 90 per cent of the damage, is due to a fungus known as Diplodia maydis. Ears affected with this fungus shrivel up more' or less, darken in co'or, and become light in weight. The kernels arc also shriveled, very brittle, brit-tle, and loosely attached to the cob. The fungus penetrates all portions of the car, kernel's, cob, nd husks, and produces many dark-brown, two-celled two-celled spores which serve to propagate propa-gate the fungus. There arc several other forms of dry rot which arc less important but cause consideable damage which seems to be on the increase. These arc also due to fungi which belong, for the most part, to the genus Fu-sarium Fu-sarium members of which cause serious ser-ious damage to quite a numibcr of our important cultivated p'ants. In the case of the Diplodia disease, and quite probably in that of the other oth-er forms, the fungus perpetuates itself it-self over winter on the old diseased cars and old stalks. It is not usually difficult to find throughout the summer sum-mer in old corn fields, where the disease dis-ease has previously prevailed, many species of old cornstalks which arc infected with this kind of dry rot. Stalks known to have been two years old have been found still producing spores. During moist periods, spoi . ooze from these stalks in abundanc-and abundanc-and arc blown singV or in masses long distances. The fungus does not, according to present knowledge, grow upon any other host, and upon deve'oping corn only on the cars. Not so much is known of the other fungi here concerned, con-cerned, but since 90 per- cent of the rot is due to Diplodia, less attention need be given to them. Disease! cars arc fruitful sources cf subsequent subse-quent infection and shouM be rcnt'.v-cd rcnt'.v-cd as promptly as possible. This can be readily done, at the lium of husking husk-ing if not before. Keep them in a separate receptacle and burn them as soon as practicable. In addition to this in fields where any enrstdcrnHe amount of disease has been found, the stalks should also have attention, whatever crop is to fo'.low. Some thing may be gained by carefully plowing them under and leaving them well covered, but burning may be required re-quired even if this is otherwise bad procedure. Such a field should not be replanted to corn for at least two years. If the first suggestion is always followed and the others are put into practice whenever necessity demands it, these serious losses may he prevented. |