Gardening Tips and Questions from Dr. Marisa Thompson and formerly Dr. Curtis Smith.

Full archives and questions can be found on the NMSU Southwest Yard Garden.

Yard and Garden - September 10, 2016

Compost

Q. I have decided that it is foolish to throw away leaves from my trees and other garden wastes. I want to learn to compost these things and use the compost to improve my garden. Do I have time to start composting now and add leaves from the trees this fall to make compost that I can use in my garden next spring?

A. Yes, you have time. You may not see everything completely decomposed, but there will be some compost formed, even through the winter. There are several factors that can help speed the decomposition of lawn and garden wastes to maximize the compost that is produced. Important factors are moisture and aeration. The fungi, bacteria, and other organisms that decompose the waste need moisture, but they also need oxygen (in typical garden composting). The compost should not be soggy, but about as moist as a squeezed out kitchen sponge or wash cloth. You should turn your compost frequently to avoid excessive decomposition and development of soggy conditions in the center and bottom of the compost. This moves the most decomposed materials to the outside, mixes it with material that has not yet decomposed (speeding the decomposition of this material), and mixes air (oxygen) into the center and bottom of the compost pile. Proper particle size will help. Very small particles hold water and provide much surface area per particle for the fungi and bacteria to feed upon, but very finely ground materials will become soggy quickly. Some coarser material mixed in will help maintain pore space filled with air close to all particles. This will allow water to drain and avoid development of soggy conditions. These coarser particles will decompose more slowly, but they may be removed by screening the compost before using. Some of the coarser material can be mixed into your garden soil to help provide aeration in the soil, especially if your soil contains much clay. A proper balance of carbon containing materials and nitrogen materials is necessary for optimum composting, but composting will still happen, though more slowly if the carbon to nitrogen ration is not optimal. Materials high in carbon to provide food (carbohydrates) for microorganisms include dried brown leaves, ground twigs, larger wood chips (good for aeration), and other such 'brown' materials. High nitrogen materials include fresh lawn clippings, kitchen wastes, freshly fallen leaves, manure, and similar substances. The optimum ratio is 30 parts carbon materials to 1 part nitrogen materials. The closer you are to achieving this ration, the faster the garden wastes will decompose and the higher the temperature that will be generated in the compost to kill disease organisms, weed seeds, and insect eggs. Proper aeration works hand in hand with the carbon to nitrogen ration to provide speedy and hot composting. Any material that reaches 130 to 160 degrees will have many diseases, seeds, and insect eggs killed. I commend you for deciding to compost. Garden wastes are a problem in landfills, causing them to fill rapidly, but properly made compost is a great addition to your garden to help the soil hold moisture and nutrients. The compost will also provide slowly available nutrients to your garden crops. A soil test is still recommended to maximize garden production, but the compost will help maximize plant use of garden nutrients that you apply. There is much more information available to help you learn composting at your local NMSU County Cooperative Extension Service office. If you live in the Albuquerque area you can apply to attend the 2016 Master Composter training which begins in October. You can find information regarding this class online at Master Composter Training. Do not delay in registering in case the training classes fill up. You will learn that there is much more to composting than what I can relay in this garden article.

Yard and Garden - March 26, 2016

Piñon Scale

Q. Do you have a hand-out on how to deal with Piñon scale? I have read about power washing the trunk and limbs, and cleaning fallen pine needles away from base of trunk. What else should I do? I just saw the little green bugs and want to know more about the insect's life cycle and how to interrupt it. - Lynn H. via University-wide Extension site

A. Piñon needle scale is one of the key pests of piñon pine trees. These small insects cover themselves with a protective covering (a scale) while they draw nutrients from the needles through their sucking mouth parts. These protective coverings appear as raised black dots on the needles produced by the tree the previous year. These insects can cause significant damage to the trees if they are present in large numbers over a period of several years. Each spring the female insects leave their protective covering and migrate downward toward the base of the trees to mate and deposit their egg masses. These egg masses are obvious because they are covered with a dirty gray / white yarn like material. The simplest method of managing these insects is to remove the egg masses by washing with a strong jet of water or sweeping them off the tree with a broom as you mentioned in your question. Collect and dispose of these eggs at a distance from your piñon trees so that the young scale insects cannot re-infest the tree after the eggs hatch. The female scale insects will die after they have deposited their eggs so they are not a concern. If you are reasonably thorough in removing the egg masses, you may be able to reduce the population of scale insects to a level that does not cause significant damage to the trees. You will need to repeat this physical removal of the egg masses every few years. If you prefer to use chemical control measures, there are products on the marked labeled for management of piñon needle scale insects. For chemical control to be effective, treatment should be properly timed. To determine the appropriate time for application of chemical control frequently inspect the tree by holding a piece of dark (or light) colored construction paper under the branches. Then strike the needles sharply with your gloved hand and look for extremely small crawler insects moving around on the construction paper. When you observe the crawler insects, it is time to spray. If you delay, the small insects will settle on pine needles produced next year and produce their protective covering and make treatment much more difficult. Your local NMSU County Extension Service office can best advise you as to appropriate chemicals to use. Be sure to read, understand, and follow all label directions when using these materials. A good publication about piñon needle scale in New Mexico is one written by Bob Cain, formerly with NMSU Extension and NM State Forestry, and his colleagues. Your local NMSU county Extension office may have some copies of 'Conifer Pests in New Mexico'. You can also find it Piñon Needle Scale. This publication discusses many conifer pests of interest to New Mexicans; piñon needle scale is one of the first discussed.

Yard and Garden - August 22, 2015

Weeds

Q. I am having a hard time controlling weeds in my garden. I do not like to use weed killers in the garden, so I pull the weeds by hand, but they just break off and come back within a few days. Is there some way to get rid of the weeds without weed killer?

A. When soil is dry it may hold plant roots tightly causing the weed to break off and then regrow as you have described. Weeds are much more easily removed from moist to even soggy soil immediately after irrigating. For some weeds this is effective even when the weeds are very close to the desirable plants. Some weeds have a more fibrous root system and may pull us much soil at the base of desirable plants, or even dislodge the desirable plant when pulled. In that case a knife or other tool to carefully cut the roots just below the soil line or below the crown of a grassy weed may allow you to manually remove the weed while doing minimal damage to the desired plant. Further away from your garden plants you can use a hoe to manually remove the weeds. I like to use a scuffle hoe that cuts the weeds roots just below the soil line. The weed can then be raked from the garden. A scuffle hoe disturbs the soil less than a chopping action type hoe which disturbs the soil and brings new weed seeds to the surface where they can sprout and perpetuate the weed problems. Another way to minimize weed problems is to use mulch to cover the soil and reduce weed growth. Some gardeners use black plastic under their plants. The black plastic eliminates sunlight needed for germination of weed seeds, but it can become hot enough in New Mexico's sunlight to burn the garden plants. A covering of organic mulch may help avoid overheating. The organic mulch (straw, wood chips, newspaper, or other biodegradable material) may be used without the plastic as well. A thick layer will also exclude light and reduce weed seed germination. Perennial weeds may still come through the mulch since they do not need light to germinate, but the mulch will help maintain soil moisture making the weeds easier to pull. Organic mulches also moderate soil temperature changes and may protect plants from our intense summer heat. The soil in direct sunlight can be 10 to 20, or more degrees, hotter than the surrounding air. Weeds you have pulled can be composted to use as soil amendment in the garden next year if they are not diseased or have not produced seeds. If your compost pile heats properly the weed and disease concerns become lessened. Another way to be sure weed seeds do not germinate next year is to put the weeds into a black plastic bag in a sunny location for a few days before putting them into the compost. The weeds should be freshly pulled so that they are still moist when you do this. They heat of the sun will kill most of the weed seeds and potential plant diseases in a few days in the solar heated plastic bag. There should then be less concern about perpetuating the weeds with the compost next year. If you eventually become so frustrated with the weeds that you decide to use chemicals, be sure to choose a product labeled for use around the desirable plants you are growing and then read, understand, and follow the directions.

Send gardening questions to Southwest Yard and Garden - Attn: Dr. Marisa Thompson at desertblooms@nmsu.edu, or at the Desert Blooms Facebook page.

Please copy your County Extension Agent and indicate your county of residence when you submit your question!