WATERING SCHEDULES AND CHRISTMAS CACTI

by Curtis Smith, Ph.D.  

Q. My cucumbers are an exotic but frightening yellow color. What has happened?

Dr. L.
via internet

A. I discussed your question with Dr. George Dickerson, NMSU Extension Horticulture Specialist, who works with home vegetable crops. He thinks that you have planted “lemon cucumber”, a cucumber that is yellow in color and is usually not as long as regular cucumbers. Another suggestion is that the cucumber is “ripening”. That is, the seed inside are maturing and getting hard and the color of the fruit is changing to indicate maturity.

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Q. The leaves have been falling from my honeylocust tree for the past two weeks. No other trees are losing leaves now. Is there something wrong with my honeylocust?

Matt H.
Albuquerque

A. Don’t worry, this is an evidence that autumn is coming. The honey locust is more sensitive to the change in day length than many other trees, so it begins dropping leaves earlier. It will also be one of the earliest to show fall color. A few other tree species are also responding to the changing day lengths, and in the next few weeks even more will be dropping leaves.

As the trees begin showing that they are going dormant, you can begin reducing the water you provide to them. In fact, drying them now will help prevent fall freeze injury if we get a sudden cold spell. The trees still need water, but some trees don’t respond well to day length changes and will remain unable to withstand a sudden cold snap. By reducing the water by watering less often, you can protect these trees. If there is a lawn around the trees, water it less and for a shorter period of time (this means the soil will not be moistened as deeply) so that the grass plants, which are more efficient water scavengers, will get the water before the trees. This is another good reason not to plant trees in the middle of grass lawns; management is much easier at times like these.

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Q. We are having a problem which I hope you might give us some help with. We have a new home in the boonies and are trying to landscape. However, the rabbits eat virtually anything we plant from cactus to flowers. Is there anything we can spray on the plants to discourage the rabbits? My wife is particularly concerned about her flowers which are mostly desert type. Thanks

Chuck S.
via internet

A. You, and many other people, have problems with rabbits causing landscape damage. I called Dr. Jon Boren, NMSU Extension Wildlife Specialist, who sent me the following information:

“I often get the question ‘How do I protect my garden and ornamental trees from rabbits?’. New Mexico is the home for the black-tailed jackrabbit and desert cottontail, which occur primarily in lowland and desert habitats. However, landscaped yards provide excellent rabbit habitats, accounting for the prevalence of rabbits in most suburban and urban areas. They are active year round, feeding in the spring and summer on succulent green plants. In fact, rabbits prefer green vegetation throughout the year when it is available. However, rabbits also will feed on buds, twigs, and bark of trees and shrubs, particularly during the fall and winter. For the homeowner, rabbits will occasionally eat the growing plants in gardens and landscaped yards. In winter they can destroy or injure ornamental shrubs, fruit trees, or berry bushes around the home.

“Rabbit repellents are often unsatisfactory for protecting plants from rabbits, especially in the long term. However, chemical repellent may provide some temporary protection from rabbit damage to trees, shrubs, vines, or garden crops. The purpose of the repellent is to make the protected plants less desirable by treating with a material distasteful to the rabbit. There have been a considerable variety of repellents recommended in the form of paints, smears, or sprays. Care must be taken when selecting the type of repellent you may chose for garden crops because many of the repellents are not designed or recommended for use on plants grown for human consumption. In addition, many repellents offer only temporary protection and must be renewed too often to justify their use. Repellents also must be used according to label instructions.

“The best insurance against rabbit damage to gardens is a tight poultry wire fence. One-inch-mesh wire 18 to 24 inches high for cottontails and 30 to 36 inches high for jackrabbits is adequate if held firmly in position by stakes. The bottom edge of the wire should be staked to the ground or buried several inches deep to prevent rabbits from burrowing under the fence. The initial cost of fencing a garden plot 25 by 50 feet is about fifteen dollars. In some gardens, this wire is still in good shape after six years.

Reusable fence panels also may easily be constructed to protect gardens. These 18- to 36-inch high panels (depending if excluding jackrabbits or cottontails) exclude foraging rabbits while allowing gardeners easy access. Panel frames can be constructed with 2- by 2-inch lumber. A 1-inch mesh galvanized wire, such as poultry netting (18 to 36 inches high), is fastened to one side of the frame. Panels can be made in various lengths to match the size of the garden. Lightweight posts, such as electric fence posts, are sufficient for support. One post should be place in each corner and at each junction of the panels. They can be fastened to the posts using malleable wire.

“Where large areas of uncultivated field or shrubby areas adjoin the garden, this is the only permanent solution to the rabbit problem. Tall grass, weeds, and brush near the garden also should be cut frequently to reduce the protective cover for rabbits.

“The use of individual protectors to guard the trunks of young trees or vines is another form of exclusion. The best are cylinders made from woven wire netting. Poultry netting of ½-inch mesh, 20 gauge strips 12 to 18 inches wide can be formed into cylinders around trees. For adequate protection, these cylinders should be braced away from the trunk to prevent rabbits from pressing them against the trees and gnawing through them.

“Types of tree protectors commercially available include aluminum, nylon mesh wrapping, and polypropylene plastic. Aluminum foil, even ordinary plastic wraps, also has been wrapped around the trunks of small trees with effective results.”

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Q. My neighbors cut down their cottonwood tree, and now I have little cottonwood sprouts all over my yard. What can I do to stop this?

A. It is not uncommon for cottonwood sprouts to develop from the roots, especially after the tree has been cut. Even if the stump is treated with stump killer, the roots often produce sprouts. You can mow them, but that will leave hard sticks at the level of the grass and these sticks may try to begin growing again. You can cut them with a shovel below ground level, and they may still try to grow. Finally, you have the option of applying herbicides. A systemic (translocating) broadleaf herbicide will not harm the lawn if used according to directions but will be absorbed into the cottonwood sprouts and translocated into the roots, killing more than just the stem. Some of the roots will survive so some sprouting may continue, but this will help stop the sprouts.

In any method, the important consideration is to keep the sprouts from retaining leaves. It takes energy stored in the roots as carbohydrates to produce the sprouts. The leaves produce food which is returned to the roots making additional growth and sprouting possible. Removal of the leaves soon after they are formed (by using a mower, digging with a shovel, or applying herbicides) prevents the replacement of the carbohydrates in the roots. In time these carbohydrates will be depleted and sprouting will stop. This is your objective.

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Q. If the leaves on my trees have spots on them, can I put the leaves in the compost, or will they cause diseases next year if I compost them?

A. We are generally taught not to compost diseased plants, but in your case I would compost the leaves. If the leaves are composted properly, the disease organisms will be killed and will not be a concern. Another consideration is that it is possible, but not likely, that the disease on the tree would affect vegetable or flower garden plants. Diseased vegetables and flowers are a greater concern because they are more likely to carry the diseases that affect garden plants.

It is possible to compost diseased plants if the disease is killed before composting. You can do this by putting the diseased plant in a black plastic garbage bag and leave the bag in sunlight. New Mexico’s sunlight intensity will create sufficient heat in the plastic bag to kill the disease organisms. After a few days, it is safe to put the plant into the compost.

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Q. Can I stop watering my lawn now that the weather has gotten cooler?

A. You should not stop watering your lawn. You can, and should, reduce the amount of water that you apply. As you do this, change the frequency of irrigation but not the amount of water apply with each irrigation. That means you should irrigate on fewer days, but each irrigation should moisten the soil to the same depth, providing the same amount of water to the soil. This will protect the deeper grass roots, preventing loss of deep roots and development of shallow roots which will be more subject to winter damage.

Because it is cooler, the grass will use less water, so the water in the soil doesn’t need to be replaced as often. The grass is still alive and growing, so water is still needed.

The type of grass you are growing influences the amount of water needed. Warm season grasses, such as Bermudagrass and buffalo grass, are becoming dormant and use considerably less water. Cool season grasses are actively growing and still using water, but because of the lower temperatures they need less water. You will need to irrigate less often in warm season grass lawns than in cool season grass lawns.

Another consideration is that the trees and shrubs in the landscape also need water now. In fact, they are very active underground at this time of year growing and extending their root systems. Water is essential, but the plants are using less water now.

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Q. My cherry tree has big problem with cherry slugs this year. What can I do?

A. Cherry slugs are the larvae of a saw fly and can severely damage leaves if the infestation is heavy. However, leaf damage at this time of year is not a major problem, but the problem may develop again next year if not treated. You can treat now, with little benefit except to reduce problems next year, or you can wait until next year to treat if the problem develops again.

There are a couple of treatment strategies. The first is chemical, and many pesticides are labeled for cherry slugs and effectively control this pest. Remember that these are not moth caterpillars, so Bacillus thuringiensis (an organic control chemical) will not work. A second treatment strategy is physical and involves the use of wood ashes from the fireplace of barbecue. Lightly moisten the leaves, then thinly apply the wood ashes to the leaves. The wood ashes are sharp, cutting the cherry slugs then drawing moisture from within the insect. This kills this particular pest. A word of caution - wear a dust mask and goggles when applying the ashes, especially if the tree is large and you must use a shovel to toss the ashes high into the tree. If you don’t protect your eyes, you will experience the effects of these sharp wood ash particles. It will be very painful! If you choose a chemical pesticide labeled for cherry slug control, be sure to understand and follow the label directions.

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Q. I have a ficus tree inside my house. It is growing rapidly and looks good. However, I noticed some little crystals at the base of almost all the leaf blades. These crystals are in the same location on each leaf. Is there something wrong?

A. It is possible that there is a small insect present causing this problem. However, the fact that all the crystals are in the same location at the base of the leaf blade in so many of the leaves suggests another answer. A rapidly growing tropical plant will often have a large quantity of water containing nutrients and sugar in its vascular tissues. At night when evaporation is less, some of this water is exuded from specialized locations on the leaf blade. As the water evaporates, the sugar and other material in the water remains behind and crystalizes. I suspect that this is the answer in the case of your ficus.

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Q. Is it time for me to bring my Christmas cactus indoors? When do I begin putting it into the closet at night to make it flower?
Amy A.
Albuquerque

A. You should bring your Christmas cactus indoors before freezing kills it. As the temperatures drop into the 40's at night or when the weather forecast predicts temperatures in the 40's, bring them indoors. If you wish, you may return them to their outdoors location during the day, but don’t forget to bring them in on cold nights. The Christmas cacti are from the high mountains of the American tropics, so they can tolerate some cool weather, but they are also killed by freezing temperatures. Regarding the time to begin inducing flowering by providing long night conditions: Now that the autumnal equinox (first day of fall) is past, we can begin treating the Christmas cacti, poinsettias, and kalanchoes with long periods of uninterrupted darkness each night. Remember to return them to the light during the day. You can do this by placing them in a cool closet each night, or leave them in an unused room in which the lights will not be used at night. You may also cover them with a black garbage bag or other dark material each evening at or before sunset if they are in a room in which the lights will be used. Room temperatures at or below 60 degrees Fahrenheit enhance flower development. Don’t let temperatures drop below 40 degrees. Be sure the plants are watered, but not as much as during their growing season. Let the soil dry between waterings. Do not apply no nitrogen fertilizer during the period of flower induction. Once the flower buds appear, don’t move the plants any more than necessary. Changes in location will cause the Christmas cacti flower buds to drop from the plants.

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Send your gardening questions to:
Yard and Garden, ATTN: Dr. Curtis Smith
NMSU Cooperative Extension Service
9301 Indian School Road, NE, Suite 112
Albuquerque, NM 87112

Curtis W. Smith, Ph.D., is a an Extension Horticulture Specialist with New Mexico State University's Cooperative Extension Service. Dr. Smith and Dr. George Dickerson host Southwest Yard & Garden, a weekly program for gardeners in the Southwest. It airs on KRWG in Las Cruces Monday-Friday at 6:30 p.m., Thursdays at 1 p.m. and Saturdays at 11:30 a.m.; on KENW in Portales on Saturdays at 10 a.m.; and on KNME in Albuquerque on Saturdays at noon and Fridays at 2:30 p.m.

Questions or Comments? Email editor@nmjournal.com