Q. Firstly, I enjoy reading your column and have learned many gardening tips with great results. Since moving into our home three years ago, the Photinia or Hawthorne patio tree has a recurring problem with discolored leaves, usually in the spring and fall. It has been treated with Bayer Disease Control, Dormant Oil and Ironite as recommended by others, along with the normal seasonal fertilization.  There are three, 4 gph emitters. Hopefully, from the photos, you will be able to shed some light on the problem. A. I am sorry this is such a late posting back to you. What you have here basically is a nutrient deficiency problem. If these problems get to advanced they can be difficult to fix. When they’re caught early, it is relatively easy. Much of this problem has to do with the soil and the use of rock mulches around certain plants that are not very tolerant of the soil conditions that develop under rock mulch. What basically happens is that the good stuff in the soil I like to refer to as organic material has essentially disappeared. When plants are grown in rock mulches there is nothing decomposing and giving back to the soil and the soil becomes what we call “mineralized” or void of organic material. Organic material in the soil is very important to some plants. Photinia is one of them. When these plants are first put into the ground the soil is modified usually with some sort of planting mix. This planting mix is usually organic in nature. This organic material modifies the soil as it is decomposing and provides many benefits to the plants that help to improve its general health. As this organic material decomposes and is lost over a period of 3 to 5 years, these benefits disappear and the plant health begins to diminish. The leaf yellowing with green veins indicates a micro nutrient problem, like iron. in our alkaline soils and alkaline water. This is why would some plants organic mulches that slowly decompose can be very beneficial. Whereas rock mulches which do not add anything organic back to the soil tends to be harmful to these plants. True desert plants are usually much tolerant of very low organic matter content in the soil. While other plants that originate from climates where the soils organic material tend to do poorly growing in rock mulches. What to do? Obviously if we can add organic material like compost back to the soil it will help. Usually, however, by the time we notice it the condition is very advanced and recovery can be slow or nonexistent. The best thing to do is to get these plants growing back under organic mulches. Organic mulches do not include bark mulches. These are almost as bad as rock mulch. Wood mulches decompose and add life back to the soil again. You can pick up this type of wood mulch free from our Orchard in North Las Vegas and a Tuesday or Saturday morning. This is a case where you have to drive in and load it yourself into containers, bags or even a pickup truck. There is no charge for this organic mulch. This mulch is made from chipping trees that are cut down in Las Vegas neighborhoods. Instead of taking it to the dump and burying it, we have provided a location we can come in and pick it up for nothing. For more information on the mulch at the North Las Vegas orchard and how to get there, call 702-257-5555.   You can also try spraying the foliage with a liquid fertilizer such as miracle Gro and iron sprays. Make sure you use a wetting agent mixed in the liquid fertilizer so that it improves its chances of entering the leaves. The wetting agent could be a teaspoon of Ivory liquid in a gallon of water. Add the Ivory liquid to the water, not vice versa or you’ll get a bunch of bubbles. This will take multiple applications of the iron chelate but only a single application of the fertilizer. You can also apply the iron chelate EDDHA to the soil around the plant and water it in. The only nursery that is caring it to my knowledge is plant world on Charleston. They have this iron chelate labeled with my name on it because I recommended so often. I do not get a kickback or anything else from recommending it. It works for reasons that would take too long to explain here. So in a nutshell, surround your plants with organic mulches that will decompose. Spray the plants with a liquid fertilizer combined with a wetting agent now. Also spray the plant with iron multiple times about a week apart and include the Ivory liquid. Apply the EDDHA chelate to the soil now. The last thing to do is cross your fingers and hope for the best. I hope this helps.

Q. I have some Early Girl tomatoes that I planted in March from plantlets that I bought. I talked to the Early Girls about a month later and told them that if they did not flower in the following week, I would feed them to the worms in my compost pile. Well they seemed to have listened, because they made lots of flowers but the flowers didn’t set fruit. What did I do wrong? A. Tomatoes are pollinated by insects, primarily bees. However, if temperatures are in the 90’s and above they have trouble setting fruit. They just don’t like those high temperatures for pollination. They set better when temperatures are in the high 60’s and 70’s up to about 85F. Other reasons for flower drop and no fruit set might be uneven watering so it is a good idea to mulch the plants. Straw is a good choice. I think a bale of straw no goes for about $8 locally. Low night temperatures below 55F can cause flower drop as well.   Also over fertilizing with nitrogen fertilizer may cause no flower development until the nitrogen is depleted a bit from the soil.   If temperatures are good, the bee does not actually have to visit the flower. Vibrations from bee activity are enough to set the fruit. If tomatoes are grown in greenhouses for instance and there are no insects in the house, the movement of the plants from vibrations caused by an electric toothbrush is often times enough to get them to set. So make sure you have pollinator activity when temperatures are appropriate for fruit set. Otherwise, gently shake them while you are talking to them. Maybe a slight physical threat might work. Another thing you can do is buy some tomato fruit setting chemicals. These are synthetic copies of natural plant growth regulators called gibberellins. It is usually applied when temperatures are cool, not hot like they are now. They are sold in nurseries or garden centers with names like tomato fruit set or the like. Follow the label directions.

Q. How do I separate the worms from my compost? I bought a thousand worms from a worm farm online. They have multiplied into the zillions but I don’t want to give them to my neighbors when I give away the compost. Is there an easy way to separate worms from compost?   A. I am not sure how you are vermicomposting but if your compost with the worms is deep enough, the worms will be mostly in the top 4 to 6 inches of the compost. The casting should be at the bottom.  I had a chance to meet the vermiculture king in Zimbabwe, Eric ‘WormMan’ Harrison, on a trip to Zimbabwe. His book on farming in Zimbabwe before the Mugabe regime, JAMBANJA – The true life story of a Zimbabwean farmer  is worth reading. A true pioneering farmer in Zimbabwe’s history. He also authored a book on vermiculture. He passed on March 26, 2012.  http://www.cfuzim.org/index.php?option=com_content&view=article&id=2337:tribute-to-eric-harrison&catid=76:cfu-press-releases&Itemid=97             So by scraping off the top layer and returning it to new compost for vermicomposting you should retrieve most of them. Also, if you can screen the compost with 1/4 inch wire mesh this should get the remainder.             . If some of the compost does not fit through the wire mesh return this also to your vermicomposting bin for further processing. You will give some “starts” away. That is inevitable. You will recover most of them             Worms like to feed on compost rather than kitchen scraps so vermicomposting can be a two-step process; first compost and then transfer the compost to the vermicomposting bin for further refining.

Q. What are the magic dates for fertilizing fescue and bermuda lawns that you had in the 9/30/2012 column? A. The magic dates, easy to remember, for fescue is Labor Day, Memorial Day and Thanksgiving, the last one for keeping it green through the low temperatures of winter. For Bermudagrass it is Labor Day, Memorial Day and Fourth of July. Use a slow release high nitrogen fertilizer made for lawns and mow with a recycling mower… one that mulches the clippings back into the lawn. The best ratio of nitrogen to phophorus to potassium (the big NPK numbers on the bag) is approximately 3:1:2 or 4:1:2 or higher in potassium (the last number like even a 4:1:4). They do  not need to be a perfect ratio but close. The number should be HIGH:Low:Medium to High. What you DONT want to use a fertilizer high in phosphorus, the middle number. Examples include 21:7:14; 12-4-8; 16-6-12; 15-5-15; etc. the best type of  nitrogen is slow release nitrogen such as sulfur coated urea, ureaform, etc. At least half of the bag’s nitrogen should be slow release. The best fertilizers I have used on turfgrass have been composted manures or vericompost. But they are expensive. Good luck!

Q. I have a non-fruiting Wilson Olive tree that was planted  last fall. It is approximately 5 ½ feet tall. I would like to prune it to be less like a bush and more like a tree with one trunk and a canopy. Since it is non-fruiting, I am not interested in pruning for better olive production and all advice on the internet seems geared toward that. I have attached some photos of the tree. Here are some questions: 1) There are two main leaders growing up in the center. I would prefer one but am afraid if I take one out it will cause a big hole in the canopy. If I removed one leader would it eventually fill back in? I understand that olive trees are fairly slow growing so I am afraid the tree would look unsightly for quite some time. 2) There are smaller branches trying to grow horizontally from one of the leaders but the other leader is in the way. 3) Since the upright leaders are already touching, what will happen if I leave both of them as is? 4) Some of the leaves have brown tips-was this just from transplanting? Not enough water? Would appreciate any advice you could give. Thank you. (To the readers of this blog I apologize. I accidentally eliminated the photo from this reader. But the tree did have two leaders growing from the same area and  nearly the same size. The tree was already fairly large. Each occupied about half of the tree canopy. When trees  have two leaders in the center ,co-leaders, they both fight for the same light and usually have very weak attachments to the trunk due to what we call “narrow crotch angles.. As the tree gets older, these places where they attach to the trunk can become weak and one, usually the smaller of the two, will split from the trunk. If this is a large limb then this might create damages sto property. Regardless, if it splits when it is large it will definitely leave an ugly tree! My reasoning in this answer was that the tree did not have a heavy fruit load to support so that was not an issue. If two leaders are to be maintained as the tree gets larger and limbs become heavier, it is best to drill a hole through both co-leaders and put a threaded, stainless steel bar through both and secure with washers and nuts. Make sure it is clearly obvious as the tree gets older. You do not want someone with a chainsaw discovering a large, hidden steel bolt!) A. I really don’t think it’s that bad. I would leave both leaders. You are right, it will leave a big hole and it will be unsightly for years to come. All your pruning cuts will be to eliminate branches so remove them at the source. Do not just cut limbs back. Remove branches at a crotch. All you have to do is remove crossed and broken branches. If two are crossed, remove the one which is more offensive. If you have new growth growing straight up, remove it at its point of origin. If there are limbs in the center interfering with each other, remove one or both if you have to. Do not leave stubs. The brown leaf tips are from a lack of water. The tree is drought tolerant but will be nicer looking with more water. I would give it about 25 to 30 gallons each time you water. Water once a week now, deeply. In midsummer go to twice a week. In winter, once every two weeks or so. Fertilize the tree now by spreading some lawn fertilizer at the base and water it in with a few gallons. Spread the fertilizer under the canopy like you were salting a steak but the guy salting it uses way too much salt and has hypertension. I hope this helps.

Thanks for keeping up with the blog. I LOVE it and always rely on it every time I need advice. You awesome! I do have a question for you and I’d really love your input.   Q. You have covered on one of your post about nematodes. Last fall, I pulled one of my cucumber plants. There were 4 plants in a row. One of the plants definitely had strange roots which I am almost positive were caused by root knot nematodes. I didn’t do any solarization because it was cold during the time and I have read that it is best to do it during the hottest months. Are these nematodes harmful to humans and my dog? Will it give me a disease or a worm if I touched the soil? You have covered that the only other way to fix this completely is through fumigation–which I can’t really do since I only do organic gardening. Can I at least plant any other vegetables in the same raised bed, or will it cause me any ill effects after I eat the fruit/veggies that it bears? I was also thinking of maybe removing the soil from the raised bed and move them to the big pots where I will be planting citrus plants. Then I will replace the raised bed with new soil. Would this work well or will it just cause problems to my citrus plants? I’d love your input. THANK YOU SO MUCH, Bob! I appreciate your the you are taking to read this. A. Nematodes are very tough to impossible to get rid of if you have them. I should say they are basically impossible to get rid of. Be careful and do not move soil from this spot to other areas or you will move the nematodes as well. Root knot nematode on tomato   Nematodes only infest plants, not animals so all animals are safe around these guys. Soil solarization will help knock back the populations but not get rid of them. There are some products like Clandosan (a naturalproduct) which are supposed to help but I would not be too optimistic. Even with fumigation it does not get rid of them buy just knocks them back. Root knot nematode on mulberry roots Use vegetables that are nematode resistant and fruit trees on rootstocks that resist nematodes. On vegetables they will have the designation “N” below the name somewhere. Other letters might also appear like “V” “F” and the like which just stands for resistant to other pest problems like verticillium (V) and Fusarium (F), two prominent disease problems. Nematode resistant rootstocks for fruit trees include Nemaguard, Citation, Viking, Atlas, Myrobalan, and Marianna. Hope this helps.

Q. I cant get my bermudagrass to look good, like the golf courses do. I think one of my problems has be mowing too low, believing it would still green up if I did that. I dont overseed it for a winter lawn. I just let it turn brown. Over the last two weeks I’ve raised the height and fertilized. Looking much better, but probably need another week for it all to get up to the same height. I’m getting small patches of darker green wider leafs, presumably poa.  Probably little I can do to stop the poa.   A. Depending on the bermudagrass it could be mowed up to one inch tall. However most bermudagrass would like to be at about 1/2 inch in height. Lower than this is for the professionals in my opinion and requires very frequent mowing to look good. The lower you mow, the more often  you have to mow to look good. When you have a thatch problem, mowing low will make it look worse. You really have to address the thatch problem this fall. If you don’t overseed, the best time to do it would be in late summer (August) so that the grass has time to mend before winter sets in. After dethatching, fertilize and water heavily to speed up the repair process. Poa will leave dark green spots when it invades bermudagrass like it has in the right side of this picture. It grows more upright than bermuda, soft and usually a darker green unless the bermuda is young and succulent. There are fewer weed problems when the grass is opened up from dethatching in the fall than the spring. When you open up a lawn in the spring there are lots of spring weeds that can invade. Yes, the small dark green patches with seedheads on many of them now is Poa. Poa is tough to control. The seed is everywhere and tracks with shoes. If your bermudagrass is an improved type you can green it up more with nitrogen and iron and this way the Poa is not as noticeable. But it will always grow a bit faster and is wider bladed than the fine bladed improved bermudagrasses. Poa is a cool season grass so if you don’t overseed the Bermuda you could spray it out in December or January with Roundup when the Bermuda is dormant. The problem will be the Poa seed that is everywhere in your lawn. It WILL come back. This is a poa seedhead or inflorescence. Poa seeds heavily and can be seen as a discoloration or graininess to the poa. I was just looking again at your response to my email. One benefit of overseeding is that it helps to eliminate some of the thatch because you must dethatch the lawn sufficiently for the seed used in overseeding can make good contact with the soil for germination. May years ago common bermudagrass would be burned in the winter to get rid of the dead surface grass and in the process any thatch accumulation. It is still recommended that bermudagrass hayfields be burned for numerous reasons including thatch removal and reduction of insects and diseases. Years ago bermudagrass lawns were also burned in the rural areas. We didn’t have a thatch problem when bermudagrass was burned in the winter. Because we cannot burn dead grass any more due to local ordinances, this dead grass remains and adds to the thatch layer. We now substitute a gasoline-driven machine (called a dethatcher, vertical mower or verticutter) instead of burning the dead grass. This of course uses petroleum, adds pollutants to the air and leaves this bermudagrass thatch that we have harvested for dumping somewhere. A  tool I have used in the past is the Red Dragon propane torch to burn debris. The model with higher BTU’s will burn grass even if it is wet. This is an advantage because you can wet down the bermudagrass dead lawn and still burn it which makes it more safe to use. There are lots of advantages to burning bermudagrass thatch but local ordinances may prevent you from using it. The burning is done just before spring growth.

Q. Some of the leaves on my Thompson Seedless grapes have started to curl/cup …see attached pictures.  There is more curling on the newer leaves; the older leaves are OK and the curling is only on one side of the plant.  The Red Flame grapes planted adjacent to the Thompson Seedless grapes are OK and no sign of curling or cupping.  These 5-gallon plants that I planted 2 years ago.  All of the plants are on a dripline system and are watered three times a week, one hour each time.  Each plant has two 1-gallon drippers so each plant is receiving 6 gallons of water per week … is that sufficient?  The plants are in a raised bed approximately 18 inches deep of premium mulch/soil.  Both of the plants have several bunches of grapes and I have already pinched off the bottom 1/3 of each grape bunch.  Any advice would be appreciated. Leaf cupping on grape. Possibly from 2,4-D or a close relative, a phenoxy herbicide known for its effects on regulating growth of plants at very low concentrations but acting like a weed killer at higher doses. A. Sounds like a great job and from the looks of it your plants are thriving. Six gallons a week is a bit light in my opinion but watch the plants and they will tell you. If you are getting some good vigorous growth from six gallons then it is enough and I would not change it. Grapes are normally deep rooted plants and can have roots that go down dozens of feet. In our landscapes this doesn’t make much sense to water deeply to accommodate roots like this so your raised bed sounds like a good depth for the plants. You are watering only to a depth of maybe 18 inches or so, so watering three times a week right now on grapes with this rooting depth makes sense to me. After grape harvest, you could cut back on the frequency of your application (times per week) if you want to but it is not necessary. But you need to maintain good soil moisture during and up to fruit harvest. It sounds like you are doing everything right. We do have two types of grape thinning; one is removing grape bunches that are too small and spacing bunches so they are not too close together (8 to 10 inches apart) AND reducing the bunch by pinching off the bottom third of the bunch. This is done as early in bunch formation as possible. You didn’t mention any pest control such as grape leaf skeletonizer, leafhopper or hornworm control so I guess you haven’t seen any. There is a fourth pest of grapes we see sometimes but not very often and that is the fleabeetle. They are small, dark blue/black rather round looking insects that chew holes in the leaves. They are usually not that devastating so we just ignore them but once in a while they can cause considerable leaf damage in the spring and fall. Now regarding the leaf cupping. Leaf cupping has to occur on developing (young) leaves since the cupping results from leaf growth in the center of the leaf while the leaf edges either don’t grow as fast or are damaged so don’t grow at all. There are three primary reasons leaf cupping can occur. First is damage from a chemical growth regulator that drifted on to your vines. Thompson seedless from reader next to affected grapes but no signs of damage. Grapes can be quite sensitive to these chemicals. One common growth regulator used by homeowners for lawn weed control is 2,4-D and sister compounds that are also growth regulators. Commonly these chemicals are used to control dandelions and other “broadleaf weeds” in lawns. If this chemical were applied to a nearby lawn (could even be 100 yards away) and there was a wind that blew this chemical from the lawn to your grape vine then that would explain the cupping. This type of damage is usually not deadly but just causes leaf distortion. The leaves are not just distorted but weirdly distorted. The leaves will not un-distort or grow back normally. They will be like that until leaf fall. The fruit is safe to eat. A second possibility are insects that cause plant leaf cupping when they are feeding. The most common insects that do these sorts of things are aphids. The feeding of aphids on plant leaves that are still growing can cause the leaves to cup downward (this is called epinasty in horticultural terms). It is thought that this type of plant reaction to the feeding of aphids is a protection for these insects from predators. Aphids of course secrete honeydew, a sugary substance made from the plant juices they suck, which attracts ants. The ants in turn use the honeydew as a food source and help protect the aphids from predators in exchange for “harvesting” the honeydew. Aphids are not common on grapes. Aphids feeding on new growth of plum causing the cupping of the leaves due to their feeding on expanding new growth. Aphids are also covering the stems. This leaves the third possibility and the one I am leaning towards. If the leaves were just coming out and expanding and if there was suddenly a very hot wind OR it got hot quickly and the grapes were tender enough to get some damage to the leaf edges then this would explain the cupping. The leaf edge would dry out from high temperatures or a hot wind and dessicate or dry out. The damaged leaf edge would not be able to grow or grow slowly. The rest of the leaf would be unaffected and would expand or grow. The growth of the center of the leaf while the leaf edge remained unable to grow or grow as fast would begin to cup. The cupping would be worse as it grew more. And of course this would happen only to young

Cathy and Bill think they have the largest ocotillo in Las Vegas. Does anyone want to challenge them? It is about 22 feet tall. Keep your eye on this posting. I will update it as I learn more. They sent me a picure of its base.

Q. Could you please give me some clue as to why my 10 year old African Sumac tree has started to get split limbs. They are splitting laterally along the length of the branch. I have had to cut off two branches in the last week because of this splitting. A. This is the first I have heard of this problem with African sumac. Who is making the decision to remove the limbs and what is the reasoning behind it? I would be curious because there are unscrupulous maintenance people who will point out something to a homeowner and recommend a job to make money. Also, there are uneducated maintenance people who will point out something to a homeowner and recommend a job to make money.             Sometimes natural furrowing of the bark can be mistaken for cracking. I have had several homeowners get concerned and send pictures and that is all it is. I have had African sumacs split due to snow loads on the branches but that is reasonable.             Most reasons for cracking would be excessive weight on the limbs. Are you sure there are no children doing pull-ups on some limbs?             This is a stretch but if the tree were growing very rapidly and pruned incorrectly I could possibly see that limb cracking might occur. Without a bit more information that is about all I can tell you with the information you gave me. Has anyone else seen this? I would love to get some pictures so I can see the problem. Pine tree limb splitting due to lack of taper along the limb. The weight of the branch on the end was too much for it after a light snow. The tree was thinned to allow for less resistance to wind to lessen blow over. Improper pruning caused the limb to not develop good taper resulting in splitting.