Two principal types of nematodes are present in vineyard soils. vitis species having the most resistance to root knot nematodes are V. champini, V. longii, and V. cinerea. Those having most resistance to the dagger nematode include V. candicans, V. longii, and V. rufotomentosa. Vines of the muscadinia section of the Vitis genus are resistant to both types of nematodes, which explains the interest in this group of vines for rootstock breeding. As for phylloxera, V. vinifera is very susceptible to nematodes, so any one rootstock will not have resistance to all nematode species, nor indeed to all nematode races. Rootstocks commonly used for nematode tolerance include Ramsey, Dog Ridge, Harmony, 1613 C, 1616 C, SO 4, and Schwarzmann.