Q. This past year our pomegranate bush had a lot of whiteflies. I know they do damage to the bush and so I want to control them organically and naturally. How would you suggest doing that? Whiteflies on this pomegranate were diagnosed to be Ash whitefly by a USDA entomologist. A. Whiteflies are a bad insect problem for any plant. I would rank them with the “hard to control” list of insects. In small numbers they can be tolerated but their populations grow so quickly that small numbers lead to large numbers very fast. For this reason, it’s important to get them under control early, as soon as you see them, in late spring and early summer. Don’t wait.             Damage is associated with their feeding. Their feeding supports a quick growth in their population as summer temperatures get hotter. They love the heat and so they’re not seen around much until June or July. Once you see them and it’s hot, watch out! You are behind the curve and they are way ahead of you!             In late May begin weekly inspections of the leaf undersides for whitefly adults. The adults look like living dandruff. You probably won’t see the eggs or immature forms because they are so small, but you will see the adult females preparing to lay eggs or protecting their young so that they can build their populations as quickly as possible. Pull these leaves off when you see them infested and dispose of them or vacuum them with a Dust Buster. This practice slows their populations way down.             Control is two-pronged. First, spray pomegranate bushes on a warm day in December and then again in January with a dormant oil. You can use the commercial brands of dormant oils and horticultural oils or you can use soybean oil, canola oil, rosemary oil or cinnamon oil.  Horticultural oil aka dormant oil are used for fall, winter, spring and early summer insect control. Spray all the branches after pruning, top to bottom, and spray a little extra shot at the base of each tree. This spray suffocates insects that might be hiding out during the winter months. It is the most important spray for controlling insects that will be problems in 2020.             At the beginning of June, hang bright yellow or bright blue thick construction paper in the tree smeared with Vaseline. Whiteflies fly toward bright yellow and bright blue objects and the Vaseline causes them to get stuck. As these traps begin to fill, replace them with new ones. It might look a little funny, but light reflected from aluminum foil repels them.             If populations are totally out of control, spray with an insecticide to get their populations back under control. As a homeowner, use pesticides when all other attempts fail. Spraying with insecticides, however, have other consequences and should be a last resort.

Q. In a previous post you talked about whiteflies.  https://xtremehorticulture.blogspot.com/2015/02/how-to-control-whiteflies-on-tomato.html https://xtremehorticulture.blogspot.com/2015/06/the-whiteflies-are-coming-whiteflies.html What do they look like and how do I know if my plants have them? Whiteflies on pomegranate A. Whiteflies are commonly found on many different vegetables during summer months, like tomatoes, squash and melons. But they are not as common to ornamental trees and shrubs. As far as ornamentals go, they can be a problem for ash trees, citrus, pomegranate, gardenia, hibiscus, iris, flowering annuals, gladiolus and some others. Whiteflies are small insects, brilliant white in color as winged adults, that suck plant juices from leaves and young stems much like aphids and leafhoppers.             If you are observant and constantly tinkering around your plants, you will notice them during the heat of the summer swarming in the air when disturbed from plant leaves like white “dandruff”. This is an indicator to look at the undersides of leaves where you will find a massive number of unwinged young’uns sucking “juice” from the plants.             If you are not as observant, you might notice sticky, sugary sap dropping on plant leaves from the feeding just above it. Or you might see columns of ants attracted to this sugary sap, going back and forth to their underground nest carrying this sugary food. Sometimes a black mold will grow on this sugary sap in more humid climates, just like it will with aphids. This black mold is called “sooty mold” which can cause lots of plant damage if left unchecked.             The adults can fly while the young-uns can’t.  So that swarm of white adults you see flying are adults only and a sure sign that feeding damage is underway.             It’s winter now so you will not see whiteflies on plants unless they are on plants in warm spots like greenhouses. They are tough to control because they are resistant to  many chemical controls. If you find them early enough, removing infested leaves might keep them in check. Repeated soap and water sprays will kill them. Winter applications of dormant oil to woody trees and shrubs in January will help suppress their numbers in the summer from overwintering adults.

Q. I am planting a 15-gallon ‘Wonderful’ pomegranate and suspicious if the plant would benefit from a deeper hole amended with washed sand to help with drainage. A. Unless there is a drainage problem, 99% of the time there is no benefit from digging a hole deeper. There is even less benefit when adding sand to the hole in any form and this practice is likely to make drainage worse! When drainage is a problem, the simplest method is to plant on mounds.             The majority of small tree or large shrub roots are about 18 inches deep. That’s all. But the soil they are planted in must drain water or the roots will suffocate or “drown”. To check for drainage, dig a hole to the same depth as the 15-gallon planting container. Fill the hole with water and let it drain. Fill the hole a second time and watch how fast it drains. Filling this whole a second time is very important because the first filling only measures how fast water enters the soil or its “infiltration rate”. Filling the same hole a second time, when the soil is still wet, measures true drainage or its “percolation rate”. 12 year old fruit tree removed and showing the depth of its roots. Most fruit tree roots are about 18 inches deep. So wet the roots to 18 inches on fruit trees like pomegranate.             If the water in the hole drains overnight, its drainage is acceptable. Only very shallow rooted plants like lawns, vegetables and annual flowers are watered daily during the summer months. When watering trees and shrubs the soil should be drained for at least one day between irrigations. This gives they soil and roots a chance to “breathe” before the next irrigation.             Take my word on this but adding sand to a planting hole, either as a layer or mixed with the existing soil, is a recipe for disaster. Adobe bricks are made from a mixture of soil, sand and organics. Keep that in mind.  

Q. We’re considering planting a fig tree grove in our school garden this year. How long typically does it take for them to produce figs ready for harvest? Main crop of figs growing on new growth. A. Figs produce fruit very quickly after planting. You should start seeing fruit produced the year after planting in most varieties. Remember, figs produce fruit on the wood that grew last year as well as the wood actively growing. First crop of figs (Briba crop) growing on older wood (right) while the younger crop of figs (Main crop and left) is alongside the older crop. Look at the age of the wood they are growing from.             Figs can be very big trees if you allow them to grow. They can also be cut back to a much smaller size. You mentioned planting a grove of figs. Their planting distances apart should be the same as their maximum height. If you plant them 10 feet apart, don’t let them grow above 10 feet tall. The main crop of figs (not the first crop) will dry up and get hard if you dont give the tree more water as it gets hotter!             Remember that figs do great in desert climates, in desert soils, in the desert heat with low humidity. But they are heavy water users much like palm trees. Water them the same as you would any other fruit tree and don’t expect production if you don’t give them enough water. They will benefit from soil covered with woodchips simply because the woodchips keep the soil moist longer. As the main crop comes on, they may dry up. This is because they dont have enough water to fully develop!!!  

 Desert lawn establishment in the Las Vegas area is lucky (or unlucky) enough to be in the transition zone for establishing lawns; both cool season and warm season grasses can make lousy lawns. Come learn why on this episode of Desert Horticulture.

Q. I put up some shade cloth to protect my fig trees from the heat. The new growth is good and the leaves look fine so I don’t think its water, but I think they can’t handle this heat. I will take the shade cloth down after the temperatures come back down to maybe 100F. A. I have grown 15 different varieties of figs over a period of 20 years and none of them needed shade cloth. They were all in full sun. They did however have lots of wood mulch covering the soil and regular irrigations applied when they were producing fruit.             The usual problem with fig fruit drying up in the heat is a lack of available water in the soil. For several reasons this problem can be resolved simply through soil improvement. Figs are an “oasis” plant, similar to palms, and the organic content of the soil near sources of water is higher. Figs in those locations have access to more water and better soils.             If you’re going to use shade cloth, never go higher than 30 – 40 %. When using shade cloth, achieve a balance between food production and food quality. In the case of figs, the fruit needs protection from birds rather than the sun.

 Learn the positives and negatives of artificial grass installed in the desert in this episode of Desert Horticulture.

Q. We moved to Las Vegas four years ago and had a professional landscape our backyard. We now have eight magnolias as well peach trees throughout our backyard surrounded by large rock up against the trunks. This rock makes it difficult to fertilize the trees and pick the fruit. Our gardener told us the trees are not getting enough water. Should I pull the rocks away from the trunk of these trees and put wood mulch around their trunks?     A. First off, both peach trees and magnolias will not like the rock laid on the surface of the soil and surrounding the trees. You will see them start to suffer from this practice in three to five years. Both prefer an “organic” mulch that can decompose into the soil and improve it. That means a four-inch-deep layer of woodchips.             When buying peach trees, they should be on a semi-dwarfing rootstock such as Citation. If bought on this dwarfing rootstock, they can be planted about ten feet apart, pruned to keep them small, the soil enriched with a good quality compost at planting time and the soil covered with four inches of woodchips, not rock. So yes, pull the rock back about three feet from the trunk and lay down four inches of woodchips instead. Young magnolia planted in fescue lawn in Las Vegas.             Magnolias? Eight of them? Wow. I’m assuming you are talking about southern magnolia with its beautiful flowers. Even in Georgia, where they belong, one specimen tree is more than enough for a large yard. Magnolias growing in Georgia can get 75 feet tall with a similar spread! These trees are NOT meant for backyard, or front yard, landscapes (desert or no desert) unless you have a huge property and water is cheap.             As these trees get older (if they do) they will become a nightmare to maintain and water. Get rid of them now before they get fully established. One tree is enough to satisfy your curiosity and you will probably remove it in less than ten years anyway.             Let’s say you keep the rocks. Using large rocks around plants has both pluses and minuses. If they are large enough, fertilizer or compost can be flushed on to the surface of the soil by washing it through the rock with a stream of water from a hose. Large rocks are also great for keeping people out. But you are right. Large rock makes it difficult to harvest and prune fruit trees. In my opinion, rock larger than 3/8-inch diameter is difficult for walking safely.

Q. I have been looking for seeds for planting fall vegetables and herbs and not having much luck here in Vegas. Where should I start?  A. Start with varieties that have done well here in the past. Dr. Wittwer’s Moapa Valley vegetable growing “Bible” is a good place to start. He mentions several older varieties that have performed well for him. I can forward a copy to you if you don’t have it.             Slowly introduce new varieties that have no production history in the desert. Be careful. Not all varieties produce well in a desert climate. Consult online vegetable seed sources like Gurneys, Park Seed Company, Territorial Seed Company, Baker Creek Seed and Grow Organic. Specialty seed sources like Kitazawa Seed and Seeds from Italy provide some interesting and heirloom seed sources.             Heirlooms don’t produce as much food as hybrids, but they are oftentimes “tastier” if you can get them to produce here. heirlooms are not as “finicky” as hybrids so they don’t require as much fertilizer and care.

Q. We have four established Raywood ash trees on our small cul-de-sac. Three are doing fine but the one directly in front of my condo is not. Just over the last few weeks, several brown dying  branches have appeared. Our landscaper said all that needed to be done was to trim the branches and give it more water. What’s your thoughts? A. Large dying branches in ash trees may be from a disease called ash decline. It can be from a lack of water but if the tree doesn’t look much better after three weeks when larger amounts of water are applied, then it is probably ash decline disease. There is no cure for ash decline and the tree should be replaced with a tree that is NOT an ash tree.   Ash decline disease or drought. Water the area under the tree with a sprinkler for an hour once a week for three weeks and find out.             Plant diseases don’t happen all at once just like they don’t happen all at once with diseases in humans or animals. The reason you see it on one tree is because it may be just beginning. Eventually if one tree has it, they will all get it whether that is in 10 years or 15 years, I don’t know. Keep an eye on the others. Remove infected trees early.