Root-knot nematode population development in macadamia varieties

Macadamia trees produce high quality nuts, and many Brazilian regions present ideal conditions for their cultivation. Aiming for financial returns during the first years of cultivation, macadamia have been grown as a coffee intercrop. Some Meloidogyne species are injurious to coffee trees, although information concerning the parasitism of these nematodes in macadamia nut trees is scarce. In this context, the aim of the present study was to evaluate the host status of seven varieties of macadamia nut tree (‘HAES-344’, ‘HAES-660’, ‘HAES 816’, ‘IAC 4–12B’, ‘IAC 9–20’, ‘IAC 4–20’ and ‘Aloha 10–14’) to Meloidogyne incognita race 2, M. paranaensis and M. exigua and to determine the life cycle dynamics of these nematodes in the ‘Aloha 10–14’ variety. For the resistance test, plants were infested with 5,000 eggs and J2 of Meloidogyne spp. Evaluations were carried out at 120 days after inoculation. The Gall index (GI), egg mass index (EMI) and reproduction factor (RF) were determined. To evaluate the life cycle of the Meloidogyne species in Aloha 10–14 roots, this variety was infested with approximately 300 juveniles of each species. Evaluations were carried out at 5, 15, 25 and 35 days post-inoculation. The progenies of all studied varieties were resistant to the assessed nematode species, and can be used as rootstock. The nematode life cycle was not completed in roots of the Aloha 10–14 variety, even at 35 days post-inoculation. Macadamia proved to be a good cultivation option for areas infested with root-knot nematodes.