Cause A fungus, Cyclaneusma minus (formerly Naemacyclus minor). Hosts include Scots, Austrian, Virginia, lodgepole, mugo, and ponderosa pine. Spores are produced on both attached and fallen needles. Rain and wind disseminate spores any time of year when temperatures are above freezing. Spores infect needles through stomata any time from April through November.
Symptoms Infected needles develop no symptoms until the end of their second growing season. Then, needles turn yellow with brown bars. White to tan fruiting bodies (apothecia) develop in the bars, but needles remain attached for several months. Severely infected trees may hold only 1 year's complement of needles.
Can easily be confused with other needle cast diseases. Needle cast diseases are identified by microscopically examining fruiting bodies and spores. Needle casts can also be confused with annual (normal) fall needle drop. Most conifers shed some of their oldest needles in the fall. These old needles often turn yellow or brown before falling off.
Cultural control
- Avoid planting in low-lying areas with poor air drainage.
- Space plants for good air circulation.
- Control weeds around the bases of trees.
- Remove and destroy cull trees in and around the plantation.
- Avoid nutrient and water stress if possible.
Chemical control Multiple applications are needed but may not improve tree grade or foliar density.
- Bravo Weather Stik at 2.75 to 5.5 pints/A. Group M5 fungicide. 12-hr reentry.
- Echo 720 at 2.75 to 5.5 pints/A. Group M5 fungicide. 12-hr reentry.
- Mancozeb-based products. Group M3 fungicides. 24-hr reentry.
- Fore 80 WP at 1.5 lb/100 gal water plus a spreader-sticker. Registered for outdoor or greenhouse use.
- Protect DF at 1 to 2 lb/100 gal water plus 2 to 4 oz spreader-sticker. Registered for field, nursery and greenhouse grown plants including Christmas trees.
- Spectro 90 WDG at 1 to 2 lb/100 gal water. Registered for conifers grown in nursery, greenhouse or landscape. Group 1 + M5 fungicide. 12-hr reentry.
Reference Merrill, W. and Wenner, N.G. 1996. Cyclaneusma needlecast and needle retention of Scots pine. Plant Disease 80:294-298.