Susceptibility of almond and cherry rootstocks and scions to Phytophthora species

Almond seedlings of Mission and Chellaston, cultivars which are commonly used as almond rootstocks, were susceptible to Phytophthora cambivora when grown in infested soil, whereas Nemaguard rootstocks were resistant. Hybrid seedlings of Nemaguardxalmond were susceptible to P. cambivora , whereas Titan a late flowering mutant of Nonpareil almond, showed some resistance. Cherry rootstocks of Colt, Mahaleb, Mazzard and Stockton Morello were not resistant to P. cambivora with Mahaleb being the most susceptible.The inherent susceptibility of almond and cherry rootstocks did not change after they had been grafted to a more susceptible cultivar.