Systemic induced resistance in Monterey pine

The pathogenic fungus Fusarium circinatum causes pitch canker of pines. Thi s study shows that Monterey pine (Pinus radiata), one of the most economica lly important pine species in the world and the main host in California, re sponds to infection Ly Fusarium circinatum in a manner consistent with syst em induced resistance. Repeated mechanical inoculations of the same trees i n the held produced progressively smaller lesions over a period of 2 years, with mean lesion length decreasing significantly from 2.89 +/- 0.42 cm to 1.04 +/- 0.17 cm. In the greenhouse, predisposing inoculations with the pat hogen induced a significant lesion length reduction, from 5.5 +/- 0.21 cm i n control trees to 4.46 +/- 0.36 cm in predisposed trees over a period of 6 weeks. Under constant environmental conditions in a growth chamber, predis posing inoculations also induced a significant reduction in lesion size, fr om 3.01 +/- 0.16 cm to 2.55 +/- 0.18 cm over a period of 4 weeks. This is t he first unequivocal report of systemic induced resistance in a conifer.