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Julie, here is something you may find interesting
Rose -- Crown Gall
See Also: Cherry -- Crown Gall Cause: The bacterium Agrobacterium tumefaciens enters plants through wounds, either natural or caused by pruning, grafting, mechanical injury from cultivation, heaving of frozen soils, chewing insects, or the emergence of lateral roots. After the bacterium enters a wound, a small piece of its DNA is transferred into the plant's DNA. The foreign DNA transforms normal plant cells in the wounded area into tumor cells. Once transformed, tumor cells proliferate automatically. The result is a gall, a disorganized mass of hyperplastic and hypertophic tissue. Pruning tools that cut through galls can become contaminated with the bacteria and spread them to cut surfaces of subsequently pruned plants. Galls breaking down in soil release bacteria which can be transported by moving soil or water. In the absence of plant roots, bacterial populations gradually decrease; however, the pathogen may survive in soil at least 2 years. Symptoms: Galls are often at or just below the soil surface in the basal or crown region. They may frequently be on roots, less frequently on aerial plant parts. Galls are usually rounded with a rough, irregular surface. They first appear as small protuberances on the plant surface. Young, actively developing galls are light green or nearly white, and the tissue is soft. As they age, galls become dark and woody. Outer portions can slough off with age. Sometimes galls have a rather smooth surface, which makes it difficult to distinguish between gall and callus growth, especially if the gall is at the plant base or at the graft or bud union. Plants can be stunted and have reduced vigor, poor foliage, and fewer blossoms. A single gall at the plant's base may be more detrimental than several galls on canes and roots. Symptoms may not develop for over a year if infection occurs when temperatures are below 59°F. Cultural control: Use only disease-free nursery stock. Inspect new plants; do not plant any rose that has galls. Avoid wounding plants, especially at planting. If root pruning at planting, soak in biocontrol agent listed below. Use plants with resistant rootstocks. Rootstocks differ widely in susceptibility. Prune off any galls on aerial parts of the plant. Disinfect pruning shears frequently. Clean shears and long soak times improve the disinfectant's efficacy. Remove and destroy badly affected plants. Preplant soil solarization has been effective for cherry nursery stock in western Oregon. Place clear plastic on rototilled ground, irrigated to near field capacity, from mid-July to mid-September. More effective on sandy loam soil. The technique may help after removing diseased plants from a bed in which roses will be planted again. Chemical control: Gallex (ready to use) painted on very young galls to reduce further development. Galls may return the following year or, if treated late, may continue to develop. Tissue surrounding the gall may be injured, especially on younger plants. Prepare the surface by removing soil from around the galled area, and allow the area to dry before application. Ferti-lome Fire Blight Spray (streptomycin) at 0.5 Tbsp/2.5 gal water. Soak root system and cut surfaces for 15 min in this solution. This works better as a wound protectant than as a cure. Cutting away galls, as label directs, may help, but all galled tissue must be removed. Getting a new, disease-free plant will work better. Foliar sprays, as label directs, are not recommended. Biological control: Agrobacterium radiobacter strain 84 has been used successfully with roses in Australia, New Zealand, and Spain but has not been effective in limited trials in the United States. Strain K 84 is preventive only. Latent infections (symptomless) and existing galls are not controlled. A suspension of strain 84 may be used as a soak or spray. Thoroughly cover grafting wood, roots, and crown. Spray to runoff. To be effective, it must be applied a few hours after wounding. 12-hr reentry. Galltrol. Nogall is a genetically modified strain of K84 that will help reduce the potential for development of resistant crown gall bacteria. 4-hr reentry. Content edited by: Jay W. Pscheidt on January 1, 2003 __________________________________________________ __ This is from our University's Extension Plant Disease Control. I thought you would find some of it interesting and helpful if for no other reason than to arm yourself with knowledge. http://plant-disease.ippc.orst.edu/d...m?RecordID=984 in case you want to look at the photos ;) Allegra |
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