Q. Dear Neil: My banana plants are 6 feet tall, produce lots of green leaves and have done so for several years, but they don’t bear any fruit. Why?
A. Bananas we have in home gardens in Texas almost never produce mature fruit. Any fruit that does form usually doesn’t have time to ripen before first frost kills the plants to the ground, so we just grow the plants as tropical ornamentals to create special effects. All of which is just fine, because the types of bananas we grow in our gardens aren’t especially good for eating even if they did actually mature.
Q. Dear Neil: Our hydrangeas have bloomed well, but their leaves are covered with black spots. Why?
A. There could be many reasons. You didn’t attach a photo so let me list just a few candidtates. Water might have stood on them when the sun hit their leaves. It might be some type of minor fungal leaf spot, or an insect might have pierced the leaves and done some minor feeding on them. It could even be associated with iron deficiency. Take a sample to a certified nursery professional so someone can see the actual spots.
Q. Dear Neil: We have two 8x10-foot raised vegetable beds and nematodes have invaded the soil. We are aware of the ways to solarize with clear plastic in the summer, but are wondering about products that might help. Can you offer any advice?
A. North Carolina State Extension folks have put together a very useful bulletin detailing nematodes, what they are, what they do and how we can control them. You’ll find it at https://content.ces.ncsu.edu/control-of-root-knot-nematodes-in-the-home-vegetable-garden. I spent 15 minutes searching for online comments about the specific product you mentioned, and I didn’t find it in any of the university (ag colleges) discussions and recommendations. I have not personally used it so I can’t offer anything more than the manufacturer and personal reports do. The people in North Carolina, however, do show great promise in dealing with nematodes if you follow their guidelines, especially in areas as small and confined as your two spaces.
Q. Dear Neil: I’m attaching a couple of photos of our mandevilla. We’ve had it for three years, but this year it is losing lots of leaves. They have unusual spots. What might be going wrong with it? Can you tell us what is causing the spots?
A. I spent 20 minutes on line looking at mandevilla troubleshooting, and there are several diseases that are known to attack them. I’m going to suggest that you send samples of freshly dropped leaves and twigs to the Texas A&M Plant Disease Diagnostic Lab, College Station, Texas 77843. Their website will have more information on submitted samples, but send them Express Delivery, and send them early in the week so they don’t sit around over a hot weekend. Send your photos with them and give a thorough explanation. There is an organism involved. I worry that it might be bacterial, and that would make it more difficult to control.
Q. Dear Neil: Attached is a photo of a 13-year-old mesquite tree. It looked great this spring, but it suddenly lost all of its leaves six weeks ago. I snapped a branch and it’s still green inside. Earlier in the summer we had a water line break, and water pooled around the trunk for several weeks. Could that have caused this? Can it be saved?
A. If that happened a few weeks prior to its losing its leaves, there is no doubt that was the cause. Mesquites need perfect drainage, which is why you see them growing on hillsides and not along riverbanks. All you can do at this point is wait it out and hope that it will bud out again, but I would be surprised. When roots are lost, so is most of the hope.
Q. Dear Neil: Our groundcover is losing leaves and appears to be dying. I do not know what type it is, but it’s growing mostly in shade and it spreads across the soil. Water is not an issue. I’m just wondering what I should do.
A. I’d almost guarantee you have trailing periwinkle (Vinca major) groundcover. Google that one and see if that’s what it looked like back in March and April. By mid-summer each year vinca leafrollers move in to tie its leaves together and make the entire bed look like someone poured scalding hot water onto the foliage. The good news is that the plants will be fine. They’ll start sending out new growth very soon now. Trim out the dead growth with a line trimmer or by setting the mower extremely high and slowly cutting your way through it. Next year apply the systemic insecticide Imidacloprid in mid-May to prevent the caterpillars ever from feeding.
Q. Dear Neil: Our little Mexican olive’s leaves are curling up. Is it doing OK? Is there anything we should be doing to help keep it healthy?
A. That’s a reaction to hot, dry weather. Tomatoes do the very same thing, except more dramatically. It’s nature’s way of helping them protect themselves against losing too much water when the humidity is so low and temperatures are so high. Keep soaking it periodically. It should be fine.
Q. Dear Neil: I planted some new sod this summer and purple wandering Jew came up through it. I called the previous owners and they had had a bed of it there. They just tilled it under and left the bed blank. Is there a product I can use that will eliminate it? I have tried digging and I can’t seem to get all of its roots out.
A. Yes. It should be easily killed with a broadleafed weekiller spray containing 2,4-D. However, read and follow label directions carefully to get the best possible results. It’s rather late in the season, so you may have some follow-up treating to do come spring. But it will be a lot easier than digging.
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