普通农业植物病理学双语课件 (4).ppt

Root-knot Nematode of Vegetable Crops
Root-knot nematodes, Meloidogyne spp., are the most important plant-parasitic nematodes in our country because of their wide host range and widespread distribution. Root-knot nematodes cause large economic damage. Yield losses is from 26% to 50%,even no Yield.
In addition, root-knot nematodes interact with other plant pathogens, resulting in increased damage caused by other diseases.
Root-knot nematodes have an extremely wide host range. All major field crops, most vegetable crops, peaches, ornamentals, and many weed or grass plants are susceptible to one or more species of root-knot nematodes.
Host vegetables include: carrot, tomato, potato, eggplant, beans, peas, onion, shallot, leeks, celery, cauliflower, cabbage, brussel sprouts, turnip, capsicum, watermelon, cucumber, gherkins, squash, pumpkin, hini, lettuce, parsley, coriander, fennel, radish, spinach, and over 2 000 other plant species.
1. symptoms
Above-ground symptoms include wilting, loss of vigor, yellowing, and other symptoms similar to a lack of water or nutrients. Infested plants grow more slowly than neighboring healthy plants. Plants often wilt during the hottest part of the day, even with adequate soil moisture, and leaves may turn yellow. Fewer and smaller leaves and fruits are produced, and plants heavily infested early in the season may die. Damage is most serious in warm, irrigated, sandy soils.
Below-ground symptoms are the swollen, knotted roots. Root-knot galls can be single , or coalesce with other root-knot galls and form a big one . It should not be confused with nitrogen-fixing nodules that develop on roots of legumes. Nitrogen-fixing nodules are attached to the side of the roots, but root-knot nematode galls are formed by enlarged root tissue .It will not "flick off" as will nitrogen nodules. Nematode galls on leeks, capsicum, shallot and members of the grass family are usually small and even difficult to see.
We can see the pear-shaped mature