Fungicidal Control of Lirula Needle Blight in Spruce Plantings : Shoot and Foliage Diseases in Forest Trees. Proceedings of a Joint Meeting of the Working Parties Canker and Shoot Blight of Conifers (S2.06.02) Foliage Diseases (S2.06.04)

Florenz

1995

S. 38-44

10 Lit. Ang.

Bandaufführung

77377

The fungicide chlorothalonil was applied to spruce trees at one site in June and July of 1984, 1985, and 1986. Lirula needle blight symptoms were not subsequently found at that site on needles that developed during any of the trial years. In contrast, disease symptoms were found on a high proportion of the needles not protected during their first year of development during the same years at a site 80km from the test site. This trial indicated that two applications of chlorothalonil could provide excellent control of Lirula needle blight. However, the lack of on-site controls left some question of whether the observed effect was due entirely to the fungicide. Chlorothalonil was applied from mid-May to late July to needles on several individual branches of two trees at a second site in 1986 and 1987. A very low level of infection occurred on needles that were sprayed several times during the growing season, while a very high level of infection occurred on needles that were not sprayed. This trial confirmed that chlorothalonil could prevent infection by Lirula macrospora. In addition, a single fungicide application in late July of 1987 also resulted in a very low level of infection. Taken together, these trials provided data to allow development of recommendations for control of Lirula needle blight on spruce. Under North Dakota conditions, chlorothalonil should be applied in early June and in early July in years when needles with mature hysterothecia are present.