Q. My front and back lawn were taken over by what I call small, nettle-head weeds. Walking on them barefoot remind me of sand spurs that I saw in the South. I have been told it was Bermudagrass weed and chickweed but it doesn’t look like the pictures of chickweed I’ve seen.  Could you please identify them and tell me how to get rid of them? Pictures of the weed sent to me. A. I could not recognize the weed from the pictures you sent. Maybe one of the readers will recognize it. It has been cut back severely. This weed appears to have a long taproot like dandelion so it could be one of the local thistles like Bull or Desert thistle. Whatever it is, it has a strong central taproot. This tells me it grows for more than one growing season and is probably a very poor competitor for space in your lawn. Mechanical Weed Control             Not the easiest, perhaps, but the best way to rid the lawn of this weed is to cut through the central taproot with a sharp knife, or forked asparagus knife, just below the soil surface. Regrowth of this weed is from the “crown” located at the top of the taproot so cutting the taproot below this prevents it from regrowing and eventually kills it. After an irrigation, perform the coup d’état. Cultural Weed Control             Thistles of all sorts are difficult to control with weed killers. But nearly all weeds can be kept out of lawns by increasing the grass density. This is done by mowing high at two and a half to 3 inches, or the top setting of the mower, and fertilizing the lawn regularly. Fertilize lawns at least four times each year with a good quality lawn fertilizer. If the lawn is tall fescue, fertilize on Valentine’s Day, Memorial Day, Labor Day and Thanksgiving. High quality compost can be substituted and gives better results and needs applications less frequently. Chemical Weed Control Triclopyrere to guess on the herbicide chemistry that might work on this weed, I would guess something okay to use in lawns but has some woody broadleaf weed control in it. This would be a mixture but I would look for either triclopyr (Garlon) or Dicamba (Banvel) in its list of active ingredients.

Q. I planted Roma, Better Boy and Early Girl tomato varieties this spring. Over 45 days later they’ve not gotten much bigger than when I brought them home from the nursery.  A. Be careful when mixing woodchips or other woody soil amendments in the soil. These woodchips require a lot of extra nitrogen as they decompose, a.k.a., rot. They will slow growth and cause yellowing if mixed in the soil without any follow-up nitrogen fertilizer applications. It is very important to add extra nitrogen fertilizer to the soil if you decide to mix anything in the soil made from wood products.             The weather has been colder and wetter than normal. This has also slowed down the growth of warm season vegetables like tomatoes, peppers, eggplant and the like. Be patient. Wall o water has been around for a long time and it works a little better than hot caps but more expensive. Be sure to warm the soil before putting transplants out in wall of water or cold soils will slow them down.             Hot caps aren’t used much anymore but those along with Wall-o-water plant sleeves were made to speed up the growth of plants during cool weather. Rediscover these nifty little garden additions. They keep plants warmer and speed the growth of warm season vegetables when weather is cool.             On the remote chance something else might be going on, inspect some roots of these plants and see if there are any small “balls” growing on them.  Root knot nematode on tomato If found this might indicate nematodes are in the soil and a problem. Nematodes infesting plant roots can slow them down as well. Not much you can do if they are present except replace the soil and plants. This is one reason container gardening can be worthwhile. The containers can be sanitized and the soil replaced more easily than in a garden bed.

Q. Last week I pulled the vines growing up the sides of my house in order to paint the exterior. These vines included hacienda creeper, Mexican creeper, Senecio, and creeping fig. Is there anything I might do to encourage them to reattach themselves up the wall or must I cut them back to the ground and wait for them to start over?  Vines for the desert Southwest If you’re looking for some vines for our hot desert climate, take a look at this pamphlet from the University of Arizona for suggestions. Pay attention to the exposure they recommend, north south east or west, shade or no shade, and the temperature they can tolerate. You are playing with fire if you select anything over 25°F for its cold, winter temperature tolerance. A. Cut them back and they will grow back quickly to their original size. This is because they are already established. Hacienda Creeper and climbing fig should climb up the painted wall again and reattach to the house on their own. These plants have established roots so they should grow up the sides of the house quickly. Creeping fig is perhaps the slowest grower of the group, but it will reestablish itself over time.             Pull some of the stems toward the wall as they reemerge and they should start climbing. Cut off stems that don’t reattach and those that do will climb faster. Senecio and Mexican creeper are twining vines so they will need some help climbing again. Adequate water, small amounts of compost once a year and regular fertilizer applications will push them to climb faster.

Q. We bought a property in Redding, California, and it has a pretty sad looking peach tree on the property. Many of the limbs are dead and the live ones are dripping sap. Do we need to get rid of this tree? Is there any way to prevent this from happening again? Not the peach tree in the question but this peach had borers in the trunk and tried to heal the damage. Note the “rolling” of growth over the damaged area. A. Peach trees are magnets for wood boring insects, a.k.a. borers, in our climate. This is the main reason most peach trees are not as long-lived as other fruit trees. This insect never enters the soil, so the soil is usually not a problem. Only the tree. If the damage to the tree is severe, remove and replace it. This is borer damage on a young Bramley Apple tree. Frequently the first 2 to 3 years are critical times for tree establishment and prevention of borers. Damage like this is usually on the West or South sides of the tree because of intense sunlight from those directions. Painting the tree trunk with dilute white latex paint is one option for decreasing borer problems during the first few years. It keeps the trunk a little bit cooler. The Death Spiral             Once trees are attacked by these types of borers, the tree frequently enter a death spiral and there is not much you can do without using insecticides. Even applying an insecticide is not a guarantee the tree will be cured. Applying a systemic insecticide containing Imidacloprid as a soil drench soon after flowering may kill borers still inside the tree and give the tree some protection for a few months. Another indicator of borers in fruit trees is the death of a limb or limbs beginning in about July. Death of a limb due to borers opens the tree for more sun damage followed by borers and can lead to the death spiral I mentioned earlier. Limbs Die during Summer Months             Limbs dying because of this insect are normally seen during the summer but the damage they cause inside the tree starts in the spring. These insects are attracted to trees damaged by intense sunlight, but sometimes they infest trees that appear not to be damaged at all. As added protection, make sure the tree is pruned, watered and fertilized so that it has a full canopy which protects its limbs and trunk from intense sunlight. It also helps to shade the trunk or paint it with diluted white latex paint. Sometimes this damage can be scraped or cut away with a sharp, sanitized knife and the area allowed to heal. It’s worth a shot. Irrigation             Make sure the tree is getting enough water by irrigating it with at least four drip emitters spaced under the canopy. With newly planted trees, these emitters should be about 12 inches from the trunk in a square pattern and more emitters added as the tree gets larger.

Q. I planted two rows of corn, separated by some peas, but one row closest to the fence never came up. I replanted that row and now one row of corn is really struggling while the other, closest to the peas, is doing well. Corn is pollinated by the wind, not insects. A lot of corn plants close together will increase the amount of pollen in the area and improve the chances of having ears that are full rather than spotty. A. Amend the garden soil with compost to improve drainage. Poor drainage can cause a lack of germination. Lightly dust the seed with Captan fungicide to improve seed germination when planted in cold or wet soils. Tear a corner of the seed packet and place a small amount of fungicide inside and shake it. Always wear gloves when planting seed treated with a fungicide. My staff in Afghanistan treating wheat seed for better germination. Protect your hands and your mouth when handling fungicides used for seed treatment.             I strongly encourage you to not plant the same type of crops in the same area as previous years. Instead, plant in new locations in the garden bed and rotate them back to this spot only after 3 to 5 years. This technique helps keep plant diseases minimized. Planting sweetcorn in raised beds requires the right time of year, a good plant density for pollination. Here sweetcorn is planted 12 inches apart in blocks.             Mixing woodchips into the soil before planting can also cause poor seed germination. Corn needs lots of nitrogen fertilizer when it’s growing. The rotting of woodchips in the soil also requires a lot of nitrogen fertilizer so make sure enough nitrogen fertilizer has been added to the soil to fuel both growing corn and rotting wood chips. Corn is more closely allied to grasses than other vegetables. Like grasses, corn is a heavy feeder of nitrogen fertilizer. A slight change in the color green in the leaves will tell you if nitrogen fertilizer should be applied. Let the plant tell you.             Peas are a winter crop while corn is a summer crop and they should not be planted at the same time in the spring unless you are prepared for a short harvest of peas. Also, sweet corn needs more than two rows planted for for its kernels to fill out the ears properly because it is wind pollinated. Plant at least four rows of corn rather than only two. Plant corn in small blocks rather than rows if the area your planting is small so the ears fill out better. Cornsilk receives the pollen shed by the top of the plant. If temperatures are too high, poor pollination results. This is seen by missing kernels in the ears. Each kernel is connected to a silk. Every silk must receive pollen for a full ear of corn.             Both corn and peas have large seeds so try presoaking large seeds, sometimes called pre-germinating, before planting to get faster germination. They should soak long enough for the seeds to swell with water. Soak large seed in tepid water for several hours before planting. This allows the seed to start the germination process without planting. But it’s important to plant them at the right time of year; peas in the fall through winter months for a winter crop and corn in mid spring or late summer for an early summer or fall crop. This is where the pollen comes from at the top of the plant called a tassel.             When pre-germinating seed, mix a small amount of your favorite water-soluble fertilizer into the fresh water, along with a tiny amount of liquid soap. This speeds up germination. When seed absorbs water at the very beginning, called imbibition, the fertilizer will be taken inside the seed with the water and early growth is more rapid. This is what everybody hopes for, a full ear of corn. This is a variety called Silver Queen. It’s a lot of work to get here.

But Woodchips Are Good! I think there is an epidemic going on of people adding woodchips to the soil as a amendment. Woodchips applied to the soil surface as a mulch is okay but mixing these into the soil can lead to problems if you aren’t careful.  Part of this trend is fueled by social media like YouTube and Internet discussion groups and experimentation by gardeners with concepts such as Hugelkulture. It works but it must be done correctly. Tomato failure. Why? Woodchips.I would not add woodchips to an area that has to be dug up every year. Everything in Moderation Adding wood debris to the soil for its improvement requires a balance between the carbon load added to the soil in the form of woodchips, water and nitrogen added to the soil at the same time to help it rot.  Add Nitrogen These sources of nitrogen help woodchips to decompose and rot without affecting other plants growing in the same area. Without this additional nitrogen, plants growing in the area yellow and may die. Seeds planted in these types of amended soils fail to germinate.             Additional nitrogen can be added by chopping up kitchen scraps, green waste from the yard such as leaves and grass clippings and even mixing in commercial fertilizers high in nitrogen such as 21-0-0. Rotting is sped up by turning it and keeping it moist.

Q.  We have an apricot tree about 5 years old.  It’s always seemed happy but this year it leafed out beautifully then last week started losing it’s healthy green leaves on one side.  Apricots are on the tree, but not developed yet. Now half the branches on that one side are leafless. A. I looked at the picture and it looks like a watering problem; not enough water getting to the upper limbs and causing drought and leaf drop. Drought occurs first on the hottest side, the sides facing the sun. If you remember, we had a hot spell just before the weather cooled off again. See if the tree is still alive             Go to your tree and bend the smallest branches to see if they are still supple. For most fruit trees, if this problem is temporary they will be supple and bend easily without breaking. If this is the case, expect the tree to produce more leaves and branches after a couple of weeks if it is given water.             Following the KISS rationale, we can eliminate the less likely disease problems, a weed killer spray drifting toward the tree, fertilizer misapplications and the like.             Now, the cause of the drought. Water shortage to these limbs could result from not enough water applied to the tree or in the right areas, or damage to the trunk or limbs by boring insects tunneling through the trunk and limbs and interrupting the flow of water. If sap is not seen on the trunk or branches or the bark is not peeling off, then we can also probably eliminate borers. Q. When is the best time  to check fruit trees for borers? A. The day after it rains.             Leaf browning and dropping from borer damage usually happens around June or July when it gets hot. But inspect the trunk and limbs anyway for signs of borers. Water, Water Everywhere             That leaves us with irrigation, which is the most likely reason particularly because of the unusual weather. A five-year old tree should be pretty big so its water needs are also large unless you have purposely kept it smaller through pruning. A five-year old tree probably needs around 25 to 30 gallons of water each time it is irrigated. This water should be applied to as much area under the canopy as possible. How Many Emitters?             The minimum number of emitters needed for a five-year old tree is four; each located about 12 to 18 inches from the trunk in a square pattern surrounding it. Six emitters arranged in a circle 18 inches from the trunk would be even better. Apply the water long enough so it penetrates to about 18 inches deep. I don’t know how many minutes this would be because each irrigation system is different. But keep the number of minutes the same as before and increase the size of the drip emitters instead if the water is not deep enough. Giving the Tree the Shaft             To judge if you applied enough water, use a long steel rod, like a three-foot length of rebar, and push it into the wet soil after an irrigation. Do this in about three or four locations to get an average irrigation depth.             This time of year, water about Three times a week if the soil is covered in woodchips. A thick layer of mulch on top of the wet soil usually saves one or possibly two days between irrigations. In June, water three times a week when it starts to get hot. If you aren’t sure when to irrigate, use a soil moisture meter like those for houseplants, to measure if the soil is dry enough to water again. Don’t trust the surface of the soil to tell you. Push the tip in the soil about 4 to 6 inches deep to get a measurement.

Q. I have six tomato plants grown from seed, all indeterminate. They were growing in two-year-old, rich soil mix containing compost that produced a lot of tomatoes last year. The leaves of the tomato plants developed okay but then they got spotty and dried up. No blossoms at all. The leafy vegetables grew well but the older leaves at the bottom of lettuce also developed black spots, became yellow and died. This gardener has been growing tomatoes this gardener has been growing tomatoes for over 30 years in the Las Vegas Valley. He seems to favor Celebrity but he grows them in the same spot year after year. We’ve got to learn to rotate vegetables so they are not grown in the same spot year after year. A. I looked at the pictures you sent. Tomato diseases are tough to diagnose with pictures but I think this might be bacterial leaf spot. I first got suspicious when you said you started these plants from seed. Then I considered the wet, cool weather, which is perfect for this disease to develop, and concluded it was probably bacterial leaf spot.  Bacterial leaf spot in North Carolina Tomato disorders from Iowa Google some pictures of this disease on tomato and lettuce and see if you think it looks like the same and let me know. Leaf spot diseases such as bacterial leaf spot can occur on lettuce as well. Google pictures of bacterial leaf Spot             Leaf spot diseases can infect the plant from seed contaminated with this disease agent. Most seed will have this disease present so applying a hot water or chlorine seed disinfection helps reduce this disease possibility. Methods for doing this at home can be found on the Internet or I can forward instructions to you.             Cool and wet weather, perfect weather for this disease, promotes bacterial leaf spot if it’s present. This disease can become a problem if the growing area has not been cleaned up and old fruit and fines are present.  Also, don’t grow vegetables in the same location year after year (implement crop rotation) to reduce the possibility of this disease, and several others, from occurring. Crop rotation can be as simple as not growing the same vegetable in the same location in a raised bed year after year.             Indeterminate tomatoes have vines that keep getting longer and longer while determinate tomatoes produce short vines and flower sooner. For earlier production of tomatoes, choose determinate tomatoes rather than indeterminate ones.  Determinate tomatoes are better for most home gardens in the hot desert anyway because you want to produce tomatoes as quickly as possible. Hot weather can come quickly and air temperatures above 95F can stop tomatoes from forming from the flowers.             If you select indeterminate tomatoes, and then fertilize them with high nitrogen fertilizers, the plants will grow beautifully but produce few flowers until they get older. When growing indeterminate tomatoes, don’t fertilize plants after planting until they begin to bear fruit.

By Robert Morris Prepared for ACDI/VOCA on March 10, 2009 Rotating fields to different crops each year is one of the most important and easily implemented disease control strategies for farmers. This practice avoids the buildup of many plant diseases in the soil. The longer the rotation before coming back to the crop, the less likely a disease will occur.  Because diseases usually attack members of the same plant family, it is best to avoid planting crops after each other that belong to the same family. Insect damage may increase when the same crop is planted in the same area over several years as well. Here are some common vegetables and the families they belong to. Tomato Family: Tomato, potato, eggplant, peppers Cucumber Family: Cucumber, melons, squash, pumpkin, gourd Lettuce Family: Lettuce, endive, salsify, Jerusalem artichoke Onion Family: Onion, garlic, leek, shallot, chive Carrot Family: Carrot, parsnip, parsley, celery Cabbage Family: Cabbage, broccoli, cauliflower, Brussels sprouts, kohlrabi, turnip, radish, Chinese cabbage, kale, collards, rhutabaga Beet Family: Beet, Swiss chard, spinach Pea Family: Peas, snap bean, lima bean, soybean Okra Family: Okra Corn Family: Sweet corn, field corn, wheat, barley, oats Some choices of crop rotations include Pea Family to Corn Family, Lettuce Family to Cucumber Family, Cucumber Family to Cabbage Family, and Cucumber Family to Corn Family. Rotating beans with a grain crop such as barley, oats, rye, wheat, or field corn or with a forage crop is very beneficial for root-rot control. One or two years in a grain crop is often long enough to prevent severe root rot when the field is not heavily infested with this disease. Some diseases that come from the soil are not easily controlled by rotation. Such diseases can live a long time in the soil and are not affected by rotation. Examples include clubroot that attacks the Cucumber Family, Phytophthora blight, and Fusarium wilt of several crops. Other diseases attack so many vegetables that they can survive indefinitely on many different plants including weeds. These diseases include Sclerotinia, Rhizoctonia, Verticillium and root-knot nematodes.  Many diseases can survive successfully because they can live on plants and plant parts left in the field after harvest. However they are unable to survive once the plants left in the field decompose. Destruction of plants and parts of plants left in the field after harvest can eliminate this problem. Plowing the field after harvest and before letting the soil rest can reduce the amount of disease that will survive.