QUESTION: I have a 'Globe Willow' that has a dark-colored sap running down the bark. It seems to be coming from under the wood near the crotch of the tree. What is the cause of this? I see some insects in this sap. Is there a bore causing the damage? The dark sap is dripping on my patio and discoloring the flagstones. What can I do?
ANSWER: Your tree is suffering from a disorder called slime flux or wet wood. These two diseases are thought to be bacterial infections, however these diseases are poorly understood. The water soaked, discolored appearance with constant bleeding of the sap at or below the branch crotches and trunk are the visual symptoms of this disease. Liquid may seep out of cracks or wounds and run down the bark. The liquid contains micro-organisms that will cause the liquid to ferment and become dark in color, sticky and smelly and some insects may feed on it. Pressure can build up under the bark from fermentation and cause splitting, and cracking. Normally the disease is not observed in young trees probably because of rapid growth which makes invasion of bacteria and fungi rare. Generally trees at least 5 years old and have developed heartwood become infected. Wilting and die back of branches may occur. Younger trees may have leaves that yellow, wilt or curl, turn colors and then drop early. Susceptible trees grown in Arizona include; ash, (Fraxinus species), elms (Ulmus species), poplars (Populus species), willows (Salix species), mulberry (Morus species), and mesquite; common, honey and Chilean (Prosopis species).
Control: Slime flux infection can aggravate wounds and cause death of bark cambium. This disease may need to be controlled in large specimen trees. Holes maybe drilled to relieve pressure under the bark. Drill a 1/4 or 1/2 inch hole at an upward angle below the bleeding and insert a plastic tube snugly and permanently into the first inch or two of the hole. This reduces the internal pressure and facilitates drainage of the fermented toxic material. Remove any dead or weak branches. Fertilize and water to keep the tree in a vigorous state. For the stains on your flagstone place a piece of cardboard or plastic to catch the dark liquid. If the stone is stained perhaps bleaching would help.
QUESTION: Are there any garden vegetables that l can plant for a fall harvest?
ANSWER: Many of the cool-season crops, those that can withstand freezing, do very well in Cochise County during the fall. In fact the fall in Cochise County is better generally than the spring to raise cool-season crops. These vegetables include the cabbage family, i.e. broccoli, cauliflower, kale and cabbage among others. Also, spinach, small beets, peas-both snap and edible pod, turnips, radishes, lettuce, mustard greens and other greens. The onion family does best when planted in the fall and then overwintered and harvested in early summer. Members include garlic, onions and chives. Prepare and plant during the last week in August or first two weeks in September. I have had broccoli, cabbage, cauliflower and onions growing the whole winter long during mild winters, pulling the plants out in May to make way for warm-season crops.