Weather conditions do not cause or originate bean anthracnose, but they have very much to do with its development and destructiveness. The spores are held together by a gummy substance which is easily dissolved in water, permitting them to be disseminated to healthy plants by means of insects, tools of tillage and in other ways. It is for this reason that tilling beans while wet with dew or rain almost always results in marked increase of anthracnose.
The treatment for anthracnose must be pre ventive rather than curative. Below are given what are now considered to be the best means of controlling this trouble : (1) Plant clean seed. If possible, secure seed from fields known to be free from the anthracnose. If seed from diseased fields must be planted, it should be hand-sorted carefully, and all seeds not perfect and bright should be rejected.
(2) Go over the field just after the beans are up, and carefully remove and burn all diseased seed lings. If left on the ground they will serve as centers of infection for the growing plants.
(3) Spray thoroughly with Bordeaux mixture. The normal strength should he used : 6 lbs. vitriol, 4 pounds lime, 50 to 60 gallons water. The addition of resin soap will add to the effectiveness of the mixture by making it spread more evenly, and it will be less easily washed off by rains (resin soap : 2 pounds resin, 1 pound crystallized salsoda, 2 quarts water ; boil until a clear brown solution is secured). Add this to one barrel of the Bordeaux. Apply thoroughly with a nozzle giving a fine spray. The first application should be made just about the time the third leaf is expanding, or earlier if the disease appears to any considerable extent. Repeat the application three or four times at intervals of ten to fourteen days or whenever the rains wash the Bordeaux off.
(4) Do not hoe or cultivate diseased beans when they are wet, as this will tend to spread the dis ease to healthy plants.
Insect enemies.
The most troublesome insect pest of the bean industry in localities where it abounds is the bean weevil (Bruchus obtectus). The adult is a brown gray beetle about an eighth of an inch in length. In the field, the eggs are deposited on or inserted in the pod through a hole made by the jaws of the female and through openings caused by the drying and splitting of the pods. In dried beans the eggs are dropped loosely among the beans or placed in the holes made by the beetles in their exit from the seed. The eggs hatch in five to twenty days,
being much influenced by temperature. The young larva' burrow into the beans and there undergo their transformations, emerging as mature beetles. The larval stage lasts eleven to forty-two days, and the pupal stage five to eighteen days, so that the life-cycle covers a period twenty-one to eighty days according to season and locality. Hence a number of generations are produced annually. In localities where these beetles abound the damage done to the mature beans is often such as to render them valueless for human food or for seed and of but little value for stock-feeding.
No effective means are known for the prevention of the attacks of the bean-weevil in the field ; hence, we must place our chief reliance on the thorough destruction of the insects in the dried seed and perhaps not attempt the production of culinary dried beans in localities infested with the weevil. Fortunately the weevil seems not to have established itself in those parts of the United States where the dried-bean industry is most developed, which is the region bordering on the Saint Lawrence river and the Great Lakes. The northern counties of New York seem to be free from this pest, while in the southern counties the bean industry is practically excluded because of it.
The weevil in beans may be destroyed by the same methods employed in the case of pea-weevil, which see. If the infestation is but partial and treatment is resorted to immediately after harvest the seed may be preserved in satisfactory condition for planting.
Literal u re.
The following publications will be found helpful. The first three are concerned with the culture of beans and the remainder with bean enemies :— Transactions of New York Agricultural Society, 1893, p. 323 ; 1897, p. 323 ; Cornell University Experiment Station Bulletin No. 210; Report of New York State Department of Agriculture, Vol. 3, 1890, p. 49 ; Transactions New York State Agricultural Society, 1892, p. 238 ; Tenth Annual Report of New York State Experiment Station, Geneva, p. 23 ; Yearbook, United States Depart ment of Agriculture. 1898, p. 233; Connecticut (New Haven) Experiment Station, 20th and 21st Reports, Part 111, p. 189 ; Cornell University Experiment Station Bulletin No. 239.