Evaluation of Strawberry Nursery Stock for the Presence of Anthracnose and Angular Leaf Spot

Abstract

Most strawberry growers in New York establish commercial fields with runner plants purchased from local or out-of-state nurseries. Two important diseases of strawberry in New York, anthracnose and angular leaf spot, are known to be associated with nursery plants. Even though these pathogens are capable of surviving in plant debris and other hosts, nurseries are often blamed as the source of the pathogen when new plantings develop disease. Anthracnose can travel on senescent tissue or on soil particles on runner transplants when shipped or, possibly, within crown tissue; Angular leaf spot is known to reside within the crown tissue. Currently, nurseries are not required to certify their plants free of anthracnose or angular leaf spot. The objective of this experiment was to determine the presence and importance of these pathogens on nursery stock. Strawberry plants of several commonly-grown varieties were purchased from nurseries across North America. Half of the plants were potted and grown in a · greenhouse to quantify viability and to observe if any disease symptoms would develop. Isolations from the crown tissue of the remaining plants were done to screen for the two pathogens. With one exception, all plants were free from anthracnose. Suspect bacteria were isolated from many crowns and PCR analysis to identify the pathogen has been completed for one quarter of the isolates; all tested negative. From the limited sampling that we have done, it appears that contamination from either of these pathogens is not, at least, a perennial problem of the nursery.