Weather changes tell roses when to go dormant

Q: I usually strip off the leaves and prune the canes to force dormancy in my roses. What’s the best time to do this? Do you have any tips on how much pruning you should do? When should fertilizer be applied in spring?

A: I am not sure why you would attempt to force dormancy. The plant will enter dormancy all on its own. Perhaps the leaves aren’t falling as quickly as you like and you want to start pruning. I’m not sure.

Plants will not be forced into dormancy by stripping the leaves off. Dormancy is regulated physiologically by two major outside forces: a decrease in the minimum temperature during the fall months and longer nights. These are sensed by the leaves and buds. Stripping the leaves off will reduce a plant’s ability to sense these outside environmental factors.

Stripping the leaves will have no effect on forcing the stems into a deep dormancy. In fact, if you remove leaves too early from plants, you may actually stimulate new growth and decrease cold hardiness of some plant parts. It is best for most plants to sense the gradual decrease in minimum temperatures and longer nights naturally as this will help take them into a deeper dormancy and improved cold hardiness.

The amount of wood to remove from roses depends on the type of rose and how tall you want the plant. There can be quite a bit of play in the size of the plant in many cases.

I would apply fertilizers to roses in mid-January. I would make smaller applications as the first few rose blooms are declining. Remember to deadhead your roses. This will help to conserve plant energy, make more blooms and decrease fertilizer losses.

I would make a another application of fertilizer just prior to the flush of flowering that occurs in early fall or late summer. Roses will flower and perform beautifully for about eight months of the year here or longer.

Q: I planted tomato plants last year. They did fairly well except about half the tomatoes were eaten by tiny ants. The local nursery said they are called “sugar ants.” I noticed these ants going into a tree in my front yard and I got rid of them with insecticide powder. I don’t want to use anything too toxic in my garden, but these things look unstoppable.

A: Well the good side of it is that the fruit must have been sweet for sugar ants to go after them. I am assuming they are not damaging the plants but only the fruit. Is there any way you can use an ant bait?

The concept of using a bait may be twofold; either use a bait that contains a poison so that it is taken back to the nest where it has a better chance of killing the colony or don’t use a poison and remove the trap when it is full of ants and replace it continually. The nice thing about ant baits that contain a poison is that the poison is typically not terribly toxic to humans or pets. It is frequently some form of boric acid.

The use of aerosol sprays or a general pesticide is to kill the ants that come in contact with it. They die before getting back to the colony and there is not enough residual to kill the nest. With baits, the poison is usually slow acting, giving the ants that come in contact with it a chance to take it back to the queen. Once in the nest and near the queen you have a much better chance of exterminating the entire nest.

If you want a real good discussion about how to use these traps and how to determine where to put traps so they will be effective, visit this Web site from the University of Nebraska, http://lancaster.unl.edu/pest/resources/antbait267.shtml.

The basic procedure is to determine what type of ant you have. Some like sugar, the so-called sugar ants, and some like protein. The type of bait you select depends on the type of ant. The more selective the ant is in its food choices, the better control you will get with baits.

The second step is to place the traps so they are relatively close to the nest and can be taken back more easily.

Bob Morris is an associate professor with the University of Nevada Cooperative Extension. Direct gardening questions to the master gardener hot line at 257-5555 or contact Morris by e-mail at morrisr@unce.unr.edu.