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- Author or Editor: J.L. Townshend x
The effects of temperature and root-lesion nematodes [Pratylenchus penetrans (Cobb)] on the growth of newly germinated `Bartlett' pear seedlings (Pyrus communis L.) were examined. At five temperatures from 10 to 30C, P. penetrans (five per gram of soil) did not purple the leaves. After 8 weeks, leaf number, trunk height, and top and root weights were reduced only at 25C. The number of P. penetrans in the roots were greatest at 15 and 20C. At 20C, P. penetrans (16 per gram of soil) caused the leaves of seedlings to turn purple, and, by 6 weeks after treatment, the nematodes had reduced leaf production, trunk elongation, and top and root growth.
Many horticultural studies require precise placement of numerous seeds in individual pots of soil. In my experiments on the relationship of inoculum densities of plant parasitics nematodes to alfalfa (Medicago sativa L.) seedling stand and growth (1), and the efficacy of a nematicide applied to alfalfa seeds (2), 20 seeds were planted per pot of soil. This seeding was tedious and time-consuming. Seeding time was reduced somewhat with the use of a multi-point dibble that made 20 evenly spaced depressions in the surface of the soil in 11.5 cm diameter styrofoam pots. However an alfalfa seed still had to be placed in each depression using forceps, the most time-consuming phase of planting. The vacuum multi-point seeder was developed to simplify these operations.