The Monticellonian., 1915-07-22
WILT AND ROOT-KN0T
Disease Attacks Many Plants
 Besides Cotton.
May Be Carried From One Field to Another by Various Agencies Weeds Attacked by Nematode
 Should Be Eradicated.

knot are distinctly stunted, but not a D. | preciably deformed. as in wilt, and have peculiar sickly yellowish-green color on both leaves and stems. In times of drought affected plants are the first to show the lack of water and may wilt slightly in the middle of the day. If such plant is dug up carefully, the root will be found to be covered with swellings or gals from the size of pinhead to one-half inch or more in diameter. If one of these knots Is broken open, numerous pearly white, rounded bodies about one-half the size of pinhead-the female ne- matodes-ean often be seen with the naked eye.
 Cotton root-knot not only causes great damage in itself, but when it Is combined with cotton wilt. as is fre- quently the case, it greatly increases the loss from wilt
 Root-knot of cotton and other crops is caused by these minute eelworms, or nematodes, which bore into the roots and live there. The irritation of their presence causes the formation of swellings or gals. The male worms are too small to be seen with the naked eye, but the females when full Of eggs assume spherical shape and may often be distinguished in freshly broken roots as described above. Each female lays several hundred eggs, and thus the worms are propagated.
 Root-knot may be carried from one field to another by any agency which will transfer some of the nematodes or their eggs. just as wilt is disseminate ed by means Of the fungus that causes the wilt disease. Drainage water is perhaps one of the most important means of spreading root-knot Nurs- cry stock also is a common agency for the introduction of the nematode into new territory. Seeding oceans. peaches, figs, mulberries or pome- granates, and young asparagus. cab bage, eggplant, strawberry. tobacco and tomato plants from infested sec tions may carry the worms in their roots or in the soil adhering to them. In the West, where the nematode oe- CUTS quite commonly in certain sec tions on the potato, the worms are carried in the tubers.
 Root-knot Attacks Many Other Farm
 Crops.
 Unlike wilt. root-knot attacks very large number of plants, many of which are important farm crops. These sub ject to root-knot injury may be divided into two groups. according to their de- gree of susceptibility. The crops most severely attacked by root-knot are as follows: Soy bean, beet, cantaloupe carrot, celery. bur clover. crimson clover, all varieties of cowpeas lex cept Iron and Brabham and other Iron hybrids). cucumber. eggplant. fig, let tuce, okra, peach, pecan, pomegranate potato. salsify. squash, tobacco toma- to and watermelon.
 Plants less severely injured by root knot are the following. Alfalfa. asparagus, bean, lima: bean, snap; cabbage. clover, sweet; collard cot ton. mulberry, onion, pea, garden: po tato, sweet; radish. spinach. straw berry, sugar cane. veteh, common; yetch. hairy.
 A few common weeds are subject to nematode injury, and should therefore be eradicated where the attempt Is be- ing made to reduce root-knot in fields The most severely injured are the bal loon vine. the maypop or passion flow CT, and the papaya or melon pawpaw Weeds less severely affected by root knot are mayweed. purslane and sweet fennel
 Such varieties of cowpeas as the Whippoorwill. Clay. Black. Unknown, Red Ripper, New Era, and others are so susceptible to root-knot that not only are they seriously injured, but the growing of them on nematode-in- fested fields greatly increases the number of worms in the soil, and con- sequently the damage to subsequent cotton or other susceptible crops. It is a common complaint of farmers in wilt sections that the wilt is noticea- bly, more severe after a crop of cow peas of a variety which is susceptible to root-knot This is due to the fact that the nematodes make points of en- trance for the wilt fungus, which then kills or further injures the plants There are few varieties of cowpeas which are highly resistant to nema- todes, including the Iron and the Brab- ham and other Iron hybrids. These should be the only cowpeas planted on land infested with root-knot
 Control Measures for Root-knot.
 The rotation and diversifcation of crops are of fundamental importance to southern agriculture everywhere and become absolutely necessary where the rootknot nematode is pres ent The principles on which such TO- tations are based are CD the use of crops immune to nematode attacks until the nematodes are sufficiently re- dueed so that susceptible crops may be profitably grown; and t2) the erad- ication of all weeds subject to root knot. The use of crops that will re- turn a profit and the building up of the fertility of the soil are also i'm portant considerations. and every farmer must work out for himself the particular rotations suited to his farm
 If land is very badly infested with nematodes as we'll as wilt, a two or three-year rotation with immune crops ----~~--~~-~~-~~-~-~~~~