Disease

Lophodermium needlecast caused by the fungus, Lophodermium seditiosum (formerly L. pinastri).

Importance

This fungus is of primary importance in nurseries throughout the Lake States where it defoliates and often kills many nursery seedlings (fig. 8).

Figure 8

The fungus can be transported on nursery stock to field locations where symptoms develop. The browning of infected seedlings after spring field planting has been confused with storage or handling problems or problems that originate in the field. Seedlings that survive in the field normally do not suffer major damage in later years. An unidentified Lophodermium sp. also attacks older foliage of sapling and pole-sized stands, but the importance of this fungus on reducing fiber production has not been determined.

Biology

Figure 9

Figure 10

Lophodermium spores are released from black fruiting bodies on dead needles during moist weather from August to October (fig. 9). The spores (ascospores) are disseminated by the wind and infect needles during this period. The fungus overwinters in attached or cast pine needles. In spring the fungus continues its development in pine needles and eventually kills them. The infected foliage (fig. 10) turns brown in May and June and falls oft during the summer. Fruiting bodies develop on these infected brown needles by the end of July, completing the life cycle.

Management Guidelines

This disease must be controlled in the nursery so that infected stock is not shipped to the field. Figure 11 shows green seedlings that had been treated with a preventive fungicide and brown, untreated seedlings.

Figure 11

Nurseries

• Irrigate nursery seedlings in the morning so they have time to dry in the afternoon. This will avoid pro-longed periods of moisture that favor Lophodermium infection.

• Do not ship infected nursery stock to the field.

• Apply a registered, preventive fungicide such as chlorothalonil or maneb, once every 2 to 3 weeks during the major infection period from late July through October. Apply more frequently if wet weather persists.

• Do not grow seedlings next to red or Scotch pine windbreaks that can serve as a Lophodermium inoculum source. Field
• Plant only Lophodermium-free stock. If you suspect infection, have seedlings examined by a pest specialist.

Nicholls, T. H.; Brown, D.H. 1975. How to identity Lophodermium and brown spot diseases on pine. St. Paul, MN: U.S. Department of Agriculture, Forest Service, North Central Forest Experiment Station. 5 p.

Nicholls, TH.; Skilling, D.D. 1974. Control of Lophodermium needlecast disease in nurseries and Christmas tree plantations. Res. Pap. NC-110. St. Paul, MN: U.S. Department of Agriculture, Forest Service, North Central Forest Experiment Station. 11 p.

Ostry, M.E.; Nicholls, T.H. 1989. Effect of Lophodermium seditiosum on growth of pine nursery seedllngs in Wisconsin. Plant Disease. 73(10): 798-800.