Infection of Red Clover Seedlings by Heterodera trifolii Goffart and Pratylenchus penetrans (Cobb).

Penetration of 3-day-old 'Kenland' red clover seedlings by Heterodera trifolii Goffart and Pratylenchus penetrans (Cobb) was investigated in 50-mm petri dishes on 1% agat or discs of Miracloth(R) (Chicopee Mills, Inc., New York, N.Y. 10018). Penetration by both nematodes increased arithmetically with increased numbers in the inoculum. H. trifolii larvae slowly penetrated all root tissue but in relatively low numbers, 25-30% of inocula. Swelling of larvae and formation of syncytia within roots was detectable 96 hr after inoculation. Initially, adults of P. penetrans preferentially penetrated the region 3-10 mm behind the root tip, but subsequently they invaded all along roots. P. penetrans penetration efficiency was high, 75-90% of inocula, and penetration was relatively rapid. When introduced simultaneously neither nematode affected the invasiveness of the other. Prior infection by H. trifolii did not affect the invasiveness of P. penetrans.