The effect of mycorrhizal fungi on the hatch of potato cyst nematodes

In the presence of potato plants cv. Golden Wonder, Globodera pallida exhib ited delayed in-soil hatch compared to that of G. rostochiensis, with signi ficantly fewer G. pallida second-stage juvenile nematodes hatching in the f irst two weeks, though the difference disappeared after four weeks. Inocula tion of potato plaits with arbuscular mycorrhizal fungi eliminated this del ay in G. pallida hatch, so that the two potato cyst nematode (PCN) species exhibited similar in-soil hatch rates. When the corresponding in vitro hatc hing activities of root leachate from uninoculated and mycorrhiza-inoculate d plants were compared, similar effects were revealed. G. pallida hatch in root leachates from uninoculated plants increased significantly from one-we ek-old to two-week-old plants, but this increase was not significant in the mycorrhizal-inoculated plants. When the in-soil experiment was repeated us ing the potato cyst nematode non-host plant strawberry, mycorrhizal inocula tion induced no significant increase in G. pallida hatch. The results indic ate that mycorrhizal inoculation of potato plants stimulates production of G. pallida-selective hatching chemicals, either hatching factors or hatchin g factor stimulants. (C) 2000 Elsevier Science B.V. All rights reserved.