Q: An oak tree at Wooton Park in Tavares has suddenly turned all brown. Does it have sudden oak death?
A: This sudden oak death was caused by lightning. When a large tree like this suddenly turns all brown, lightning is the main suspect. You can see from the photo that the lightning caused gashes in the trunk. Lightning strikes usually cause gashes and bark to be blown off and kill the tree quickly.
Q: I think I have sedge growing in my lawn. How can I control it?
A: Sedges look a lot like turf grass, but they are not the same. Sedges grow in individual clumps and usually have triangular stems. Purple and yellow nutsedge have underground runners and tubers that make them difficult to control. There are herbicides that are specific for sedges that will not kill turf grass, however each type of turf grass is a little different. Check http://edis.ifas.ufl.edu/ep492 for specifics on what to use with each type of turf grass.
Q: One of the three Canary Island date palms in my yard is dead. Will the others soon follow, or is there anything I can do to stop whatever is killing my palms?
A: There are several diseases that are fatal to date palms specifically that may spread to others in the vicinity. For more on palm diseases, go to http://flrec.ifas.ufl.edu/palmprod.
Texas Phoenix palm decline is caused by a mycoplasma, similar to lethal yellowing disease, that is spread by some type of piercing/sucking insect. If you notice more than usual of the lower leaves turning brown, the newest leaves collapsing and dying, the flowers all turning black and all the fruit dropping, you most likely have this disease. The only protection from it is periodic injections of antibiotic.
If the leaves all seem to be hanging low and pull off easily, you may have Palmetto weevil. If you inspect the bases of the leaves and see tunneling, large grubs and pupal cases that look kind of like shredded wheat balls, this is your pest. Several insecticides are listed for use as a crown drench and some systemic insecticides can be applied as a root drench to keep these insects from spreading to the other palms. Once the grubs have eaten the bud of the palm, it cannot be saved.
Fusarium wilt is another possibility. With Fusarium you may notice some of the older leaves having one side of the leaf green and the other brown with a dark streak down the main stem of the leaf. If the palms are over-pruned you may never see this symptom, you may only see the whole top turn brown. This disease is spread by pruning, so be sure to sterilize your pruning equipment between each palm. A sample sent to a plant pathology laboratory will be the only way to confirm, and there is no cure or preventative treatment.
A final possibility is Ganoderma butt rot. This disease usually progresses very slowly over six months or more. More and more of the older leaves will turn brown, until there is only the new spear leaf and then that will die also. You may or may not see a shelf fungus growing out of the base of the trunk. This fungal disease grows in the base, or butt, of the palm until the whole base is rotted out and not functioning to transport water and nutrients to the top of the plant. There is no cure for Ganoderma, and it can affect all palms. In this case you should remove the palm, do not grind it up to make mulch, and replant with anything other than a palm.
Visit the Discovery Gardens and our plant clinic with your plant problems and questions from 9 a.m. to 4 p.m. weekdays at the Ag Center, 1951 Woodlea Road in Tavares. For details and class registration, go to lake.ifas.ufl.edu.
Juanita Popenoe is the director of the UF/IFAS Lake County Extension Office and environmental horticulture production agent III. Email jpopenoe@ufl.edu.