What’s New – Excerpts from Spring 2011 Earth-Wise Newsletter

Marssonina Blight May Have You Seeing Spots

Marssonina blight (Marssonina populi) is a fungal pathogen that is native to aspen forests of the Rocky Mountain region. Marssonina is always present to one degree or another, but incidents of the disease are usually more common in years with wet spring weather. The damage to host trees is mostly aesthetic, consisting of dark brown blotches on the leaves and premature leaf drop. However, if a tree is badly infected several years in a row, it may become more susceptible to secondary insects and diseases that pose a more serious health threat. An important step in preventing Marssonina infection is improving cultural conditions. Because the fungus overwinters in previously infected leaf debris, it is important to thoroughly rake up leaves and remove them from your property. Reducing humidity levels in aspen stands is also key. This can be done by pruning crowded plantings to allow more air flow and by avoiding irrigation water landing on the leaves of aspen trees. Preventive fungicide applications are another treatment option. The first application is made at bud break followed by a second treatment 10 – 20 days later. Ideally, these applications would continue until environmental conditions that favor the disease formation have passed. However, the number of treatments required for ideal control is not a practical solution for most homeowners. Thus, Earth-Wise typically does two preventive sprays – not in an attempt to completely eradicate Marssonina from your property, but rather to keep the disease at non-damaging levels. Given the spring weather that we experienced in 2009 and 2010 and the high levels of Marssonina blight that we saw in the area, it is safe to assume that there are a greater number of fungal spores waiting to infect trees this spring. Please contact us if you have questions regarding this disease and how it may impact your aspen trees.

Aeration – It’s Not Just for Lawns

Proper soil aeration is critical to the health of your trees because roots need oxygen to grow and function properly. An ideal soil is made up of 50 percent solids (silt, clay, sand and organic matter) and 50 percent pore space (air-filled and water-filled pores). However, very few landscape soils fit this profile. Typical development and land use compacts the soil and eliminates pore space, creating an unhealthy environment for your trees’ roots. Fortunately, there is a remedy. Properly amending the soil with organic matter, fertilizing and mulching will all help reduce soil compaction. A recent study showed that the above applications along with air tillage of the soil reduced compaction for at least three years after the treatment (Wells et al. 2009). You can’t have healthy trees without healthy roots. And healthy roots require aeration.

Green Solutions from Earth-Wise

Earth-Wise remains committed to providing quality plant health care services while leaving a small environmental footprint. To this end, we have always utilized cutting edge application methods and products: Applications made via soil/trunk injections and low-volume backpack sprays are examples of tools used to minimize the risk of exposure to non-target areas. Products such as horticultural soaps and oils, neem oil and pyrethrins allow us to effectively control many common landscape pests such as aphids, mites and scale insects. The use of pheromones offers some control of bark beetles like mountain pine beetles, spruce beetles and Douglas fir beetles. We can also maintain healthy, vigorous trees with an organic fertilization program. If you would like more information about moving your treatments in an organic direction, please contact us to discuss the specific options for your landscape.