Plant Diseases


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Bonide Solutions:
There are several different kinds of needlecasts including Rhabdocline needlecast of Douglas Fir, Cyclaneusma and Lophodermium needlecasts of pines, Swiss needlecast, and the most common Rhizosphaera needlecast of spruces. Rhizosphaera needlecast has been a common issue for Colorado Blue Spruce that are grown in humid conditions where there is poor air circulation around the tree. Prevention is key so do not plant trees too close together. Rhizosphaera needle cast causes needles to turn purplish brown and fall from the tree, usually from the inside of the tree working out and from the bottom of the tree working up.
Fungicides such as Bonide’s Fung-onil do not cure needles already infected, but they protect needles that have not been infected and the newest growth as it emerges. Due to the new growth emerging in the spring, the ideal time to make spray applications to conifers is prior to and/or as new growth emerges.