Minimize overhead watering and opt for mulching. You can prevent the condition by choosing disease-resistant cultivars that have to be planted in locations with enough sunlight and air circulation. In such cases, remove the tree completely. If the main stems develop cankers, then the condition is systemic and there is no point in pruning. Don’t forget to disinfect the pruning tools. Once they gain entry, the bacteria spread rapidly and the whole tree may wilt and die.Ĭontrol and Prevention: If the condition is limited to leaves and small branches, then prune and dispose them properly.

They may also enter through the natural pores on the tree. They require entry points in the form of wounds, scratches or abrasions on trees. They get transmitted through wind, water or contaminated soil. The bacteria (like Pseudomonas syringae) that cause leaf spots or blight are usually found in the debris of diseased trees. If the tree has a dense foliage, pruning will facilitate air circulation, which will be beneficial for preventing such infections.Ĭauses: As compared to fungal leaf spots, bacterial leaf spots are not common in magnolias. Use fungicides as per the instructions of a horticulturist. Fungicides may prevent secondary infections, in a tree that is already infected with fungus. Fungicidal sprays may work as a preventive measure. Dispose the residue and disinfect the tools. Avoid watering the foliage and prune infected and weak branches. Though mild infection may not harm the affected tree, heavier and repeated episodes along with premature leaf dropping may affect its growth.Ĭontrol and Prevention: First of all, prefer disease-resistant varieties while planting magnolia. Crowded planting could as also be a contributory factor. So magnolia trees that are in wet, shady and humid locations are at the risk of developing fungal leaf spots. Once the spores settle on a magnolia, they germinate and grow, as and when the conditions become favorable. They produce spores during spring and summer and the spores are carried by rainwater, wind and even insects. Live scales will “bleed” when crushed, dead scales will be dry and will not “bleed”.Causes: The most common cause is the fungi that survive in the debris of affected trees. Since the females leave their hollow brown shells behind that stick to the plant for many months, check to see if scales are alive by crushing the shell. As scale population is reduced in following years consider applying a stand-alone soil treatment of Transtect in early spring or Xytect in late fall. Expect some adult feeding and sooty mold production in year one, if spring applications of Transtect or Xytect are applied.Ī combination approach of a systemic soil treatment and a fall crawler stage foliar spray may be used to provide additional control of heavy initial scale populations. Heavy magnolia scale populations will require two years of systemic soil treatments to reduce adult feeding and sooty mold production. The magnolia scale’s non-synchronized (crawlers hatch and settle for a prolonged period of time in late summer/early fall) life cycle makes timing of spray products operationally challenging. Reports from arborists and university scientists have yielded inconsistent control from both crawler sprays and soil applied systemic treatments. Magnolia scale can be a challenging soft scale to control. Promote health and vigor with proper irrigation, mulching, proper pruning and prescription based fertilization practices.Transtect Infusible or Xytect 10% as a tree injection treatment for trees that cannot be treated with foliar sprays or other systemic options. Foliar spray insecticides combined with 0.5% to 1.0% horticultural oil can be applied after the majority of the crawlers have hatched and settled in late summer/early fall. Proper timing and a combination of sprays and soil applied treatments may be required in the first year of treatment to get high pest infestations under control.ĭormant oil treatments can assist with control (should not be counted on as a stand-alonec ontrol) and should be applied in early spring. Xytect can be applied in late summer/early fall (same time as fall insecticide sprays) of the previous year or Transtect can be applied during leaf emergence in early spring of the current year to kill overwintered instars. The magnolia scales non-synchronized (crawlers hatch and settle for a prolonged period of time in late summer/early fall) life cycle makes timing of spray products operationally challenging.

Magnolia bacterial blight