Studies on plant parasitic nematodes homogeneously labeled with radiophosphorus

Summary o 1. A quantitative study was made of the volume and phosphorus content of root-knot and golden nematodes during different stages in their life cycles. 2. Galled tissues of plants infected with root-knot nematodes accumulated P 32 from labeled nutrient at a lower rate than uninfected roots of the same plant. Infection in one part of a root system, therefore, does not impair the ability of uninfected roots of the same plant to take up phosphorus. 3. The phosphorus content of the nematode population of an infected tomato plant makes up no more than 10% of the total P of the plant. It follows that the unhealthy condition of the plant is not caused by the parasite “robbing” the host of this vital element. 4. Less phosphorus is translocated out of galled roots than out of ungalled roots.