San Antonio Express News
Sunday, February 15, 2003
By Nathan Riggs
It’s hard to believe that February 2004 is already half over! Time certainly flies and this month is one of the busiest of the year for the staff at the Bexar County Extension office. Even though we are very busy and stretched to the limit, we are not too busy to continue providing relevant information to anyone who needs it. This week’s article contains important gardening information for the mid-February period. Our topics include pruning roses and crepe myrtles, as well as dealing with those notorious cut ants.
With Valentines Day fresh in our minds, it is the perfect time to talk about pruning your roses to prepare them for the spring season ahead. Roses are usually pruned twice a year–in October and again in mid-February. The late winter pruning is the most severe, as this is the time to truly renew the plant for spring growth.
With hybrid roses, as much as one-half of the shrub may be removed, including all non-productive, woody canes and canes which cross one another. One can safely remove a mass of inside growth (center of the shrub) in order to promote increased air circulation and available sunlight as the new growth appears, thus counteracting mildew and blackspot. These two common rose diseases thrive in our wet, humid spring weather. The standard rule is to remove all stems which are smaller than the width diameter of a pencil. Remove all suckers, and on the healthy 6 to 8 canes that remain, cut at a slight angle just above the dormant bud.
Antique roses do not require such drastic pruning. One needs only to remove the dead wood, prune some of the center mass to promote air circulation, and reduce shrub height by one-third at the most. Spring blooming climbing roses MUST NOT be pruned until after they the first bloom in spring, so keep that in mind.
For those fortunate enough to own the lovely and hardy crepe myrtle, now is also the time to give them a trim. Crepe myrtles should not be trimmed or pruned in a severe manner. You have probably seen them cut back so severely that the limbs look like bones! This is called “dead-heading” and is not the proper procedure to follow if you wish to maintain a healthy plant. Instead, trim the spindly sprouts from the main branches, and trim off last year’s bloom remnants. Trim off a few inches from the ends of the branches, but not to the point where only the trunk remains. Crepe myrtles that are trimmed severely take longer to bloom than those with more moderate pruning. Crape myrtles are now available in a multitude of colors and sizes.
For more detailed information on pruning, roses and crape myrtles, send a self addressed stamped envelope to Texas Cooperative Extension, 3355 Cherry Ridge, Ste 212, San Antonio, 78230.
Lastly, we will talk about cutting of a different kind. Let’s talk about the pruning of precious plants that is performed by those notorious leafcutter ants! For those who are besieged by cut ants, the torment of watching the leaves of a prized rose, crepe myrtle or other ornamental, disappear into a cut ant tunnel can be unbearable.
Cut ants are very active in south Texas throughout the fall, winter and spring. They strip the vegetation from plants, carry the harvest to their nests, and grow a fungus on the leaves that is eaten by the ants for nourishment. This makes cut ants very hard to control with regular ant baits. Cut ants forage for food up to 600 feet from their nests so most people only see their foraging tunnels and not their actual nest areas. This explains why treating these cut ant holes in the lawn only results in a temporary halt in the destruction.
Controlling cut ants is a frustrating task, but there are a few procedures the homeowner can use to slow down these eating machines. Applying small amounts of a dust insecticide in each hole appears to be somewhat effective. Look for dusts containing acephate, permethrin, deltamethrin or pyrethrin for this type of application.
While ant baits for cut ants have generally failed in the past, there are some baits on the horizon that have some potential to turn the tide in the gardener’s favor. A bait called Grant’s Kills® Total Ant Killer Bait is on the market that has shown some success against cut ants. Most treatments with this product require a second application to be successful.
The hope for success on the horizon is the arrival of a bait product Blitz. In field tests, this bait has killed cut ant colonies anywhere from two weeks to two months after the first application. A product similar to Blitz, called Volcano, is sold in East Texas to pine foresters and has had spectacular results on cut ants. Volcano costs ~$32.00~ per pound, but is a good value for those who have used it.
Don’t forget that now is also the best time to prune your live oaks and red oaks to prevent oak wilt transmission by sap beetles.
This article was written by Nathan Riggs, Extension Agent-IPM with Texas Cooperative Extension in Bexar County.