Technique for Quantifying Injury to Seedling Soybeans by Pratylenchus penetrans Without Sacrificing the Plant.

Lesion nematodes (Pratylenchus spp.) are abundant in soybean fields in Illinois and Indiana (2, 3) and are capable of causing damage to soybeans (1, 5). Use of nematicides to protect soybeans is not economical. Breeding res is tan t varieties may be a more logical approach, but a technique which might prove adequate for fast and effective screening of s o y b e a n lines has not been available. A technique is described herein which might be satisfactory. Seeds of soybean (Glycine max L. 'Clark 63') were soaked 30 min in 10% commercial bleach solution (0.5% NaOCI) and rinsed in sterile water, and four seeds placed hilum down in a diSPo® growth pouch over holes punched in the trough o f the paper wick (diSPo pouches are made of clear plastic, 16.5 × 17.5 cm, and contain a paper wick folded at the top to form a trough). Preliminary tests showed that it was not necessary to sterilize the pouches (5). The charged pouches were placed at 25-27 C until the germinating tap root was 0.5-3 cm long (18-36 hr). Seeds that failed to germinate were r e p l a c e d w i t h a supplemental supply o f seedlings. Pratylenchus penetrans, obtained from callus culture, were used as inoculum. From 1000 to 40,000 total specimens in water suspension were added/pouch in 3, 5, or 10