Resistance levels of <scp>S</scp>panish conifers against <i><scp>F</scp>usarium circinatum</i> and <i><scp>D</scp>iplodia pinea</i>

Abstract

Summary Pitch canker, caused by F usarium circinatum , and D iplodia shoot blight, caused by D iplodia pinea , are both damaging to pines ( P inus spp.) grown in plantations throughout the world, including Spain. To assess the potential for interspecific differences in susceptibility to contribute to the management of pitch canker and D iplodia shoot blight in the Atlantic region of S pain, the present study was undertaken to characterize the susceptibility of six pine species ( P . sylvestris , P . nigra , P . pinaster , P . radiata, P . halepensis and P . pinea ) and Douglas‐fir ( P seudotsuga menziesii ) to F. circinatum and D . pinea . Based on inoculations of 2‐year‐old trees, P s. menziesii , P . pinea and P . nigra were the most resistant to F . circinatum , with lesion lengths ranging from 3.7 to 21.5 mm, 2.2 to 12.6 mm and 2.8 to 30.9 mm, respectively. At the other extreme, P inus radiata was the most susceptible, sustaining lesions that ranged from 8.5 to 74.8 mm in length. Pinus sylvestris , P . pinaster and P . halepensis showed an intermediate response to F . circinatum . Broadly similar results were observed in inoculations with D . pinea , with P s. menziesii being relatively resistant and P . radiata being highly susceptible. Consistent with these results, field surveys revealed no pitch canker in stands of P s. menziesii and low severity of D iplodia shoot blight, whereas P . radiata was severely affected by both diseases. Our findings suggest that selection of appropriate species can greatly reduce the risk of damage from two important canker diseases affecting pine plantations in the Atlantic region of S pain. Furthermore, intraspecific variation in susceptibility implies that selection may allow for the enhancement of resistance in otherwise susceptible species.