Loquat, grapevine, peach tree troubles
This week, viewers have fruit tree questions. Armando Reyes has a loquat tree that was doing great. But the last two years, a part of the bark seemed to be cracking and now it’s breaking off.
We checked with Jim Kamas, fruit and nut specialist for Texas A&M AgriLife Extension in Fredericksburg, and he tells us that this is a delayed symptom that developed from a spring 2017 freeze. Jim suspected, and Armando confirmed, that the injury is on the south/southwestern side of the trunk, and says that this is a classic case of the sun beating down on a trunk and elevating the temperature under the bark. That causes the affected tissue to de-acclimate from winter hardiness more than the other side of the tree. When the sun goes down and the temperature drops, the southwestern side gets cold injury but the northeastern side does not. It’s quite common for the symptoms of this type of injury to be delayed by a couple of years, once the rest of the trunk grows and the damaged tissue begins to slough away, unable to grow with the rest of the tree. There’s nothing to be done for the wound at this point, just keep it watered and growing as normally as possible. The tree shows signs of healing itself and should be fine. Loquat is a sub-tropical species and this kind of winter injury is to be expected in our climate.
And Linda Gurasich has a problem with her four-year-old peach tree. This is the first year the peaches have stayed on the tree, but there’s something oozing from them. Once again, Jim came to the rescue. The answer: stink bugs!
These insects feed on young fruit by inserting their sword-like proboscis to steal its sugary goodness. Once they’re done, the bugs move along, but the fruit continues to develop. As the plant sends more sugars into the fruit, some of the sap will ooze out of the wound created at the feeding site, which will harden once exposed to air.
There are no larvae inside the fruit, but the open wound does provide a good entry site for brown rot fungus, which is common in wet years and for which there’s really no good solution. Stink bugs are harbored in nearby weeds, so be sure to keep the area around your fruit trees weed-free to minimize infestation.
Jim also had the answer about Kristin and Ryan Harvey’s four-year-old grapevine with rotting fruit. The vine looks fine otherwise, and this year it set tons of fruit. This is black rot, the Achilles’ heel of organic grape production. It’s a really tough fungal pathogen that will clobber us in wet years.
It wasn’t all problems this week, we also got some great viewer photos! David Mercado lightly pruned his fig trees and got a bonus indoor arrangement. They worked beautifully in tall vases in this charming vignette. In another vase of florist flowers, he added sprigs of his blooming vitex tree.
And Charlotte Warren discovered an unusual find on her friend Suzanne Stewart’s property in Western Travis County. This is native crested coralroot orchid, Hexalectris spicata, which lives off fungi and decaying organic matter. It contains no chlorophyll and cannot photosynthesize.
Unfortunately, we’re beginning to hear from more viewers that dreaded rose rosette has found its way to their gardens. Dick Peterson, conservation and environmental expert, and former Texas Rose Rustler, reports that the disease has struck his antique roses, like Martha Gonzales. He’s noticed that Knock Out roses in his Round Rock neighborhood are succumbing, too. Dr. Kevin Ong, Director of The Texas Plant Disease Diagnostic Laboratory at Texas A&M, has seen first-hand how this issue wipes out entire swaths of roses as it marches across the map, so we asked him for suggestions on replanting. The newest research indicates that rose rosette is spread by eriophyid mites. Dr. Ong suggests waiting at least a month, because many roses produce suckers from the roots, a source of infected tissue, which can be picked up and spread by new eriophyid mites. Also, be cautious about replanting roses in areas such as Dallas/Fort Worth, parts of Oklahoma, and other areas of the countries where many roses have succumbed to rose rosette. Disease prevalence is very high in these areas, so re-infestation is quite likely. To find about more about rose rosette and see a map of its spread, visit roserosette.org. If your roses have been infected, you can also add information about your site to assist with research on this devastating disease.
Now, here are some really pretty moths spotted by viewers Jamie Dollinger and Santiago Lopez. These are Southern Flannel moths, both male and female. As cute as these adults are, their larvae are among the most venomous to touch. Called puss caterpillars, and also referred to asps, they feed on many shrubs and trees, including hollies. Avoid touching the fuzzy-looking orange-hued caterpillars, since the spines can cause extremely painful rashes. Thanks to the helpful folks at bugguide on Facebook for their assistance in identifying this one!
In South Austin, Cleo (Pe-tree-sek) and her five-year-old son Graham started five kinds of sunflowers in late spring, to see which will grow taller this summer. Since they live on a greenbelt, snakes come into the garden, so, they got two Pygmy/Nigerian Dwarf goats since Cleo told us that snakes don’t like all the stomping about from goats. To keep them occupied and happy, Cleo’s husband (Shay) made the goats their very own seesaw and platform swing!
From Lebanon, Dr. Shelia Graham Smith sends pictures from her work at a university this summer. I bet you’ll recognize many of them, including star jasmine, blooming right along at the same time as ours back here at home, as well as outstanding geraniums, abundant loquats, and Angel’s trumpet, Brugmansia.
We’d love to hear from you! Click on centraltexasgardener.org to send us your questions, videos and pictures.