Q. My question today is, how to deal with white grubs in established landscape plants.  I have seen them in a few yards in Mesquite, NV this year.  Is it just a seasonal thing?  I just found 7 more yesterday in Mesquite on one property.   How do I get rid of any there now and how to prevent in future?  Are some plants more susceptible than others?  Some of the plants I found them in the dirt:  Eucalyptus just planted, texas mountain laurel, african sumac, and I think they got a bunch of myoporum, agave parryii, Santa Barbara Daisy. A. I will tell you as much as I know about these grubs. They like to feed off of decaying organic material. I think sometimes they get confused between dead and dying organic matter and small roots of plants like Lantana and so you find them everywhere.  I guess I just figure that wherever the soil is been enriched and there’s healthy plants you’re going to find these critters. They mature into June bugs, metallic green June beetles, rose chafer’s and just about anything else in that particular family of bugs.  They are fairly easy to kill with a soil drench of Sevin insecticide but the problem is which plants do you drench? All of them? The adults pupate around May or June so if you are going to treat plants with an insecticide then you’re going to do it fairly early in the season or fall. It doesn’t make much sense to put down an application close to may because the are adults are going to emerge and fly around and meet and be back in the soil by July or so.  You can try spreading the bacteria that are supposed to kill them long term or the nematodes. These biological control insecticides may take a bit longer to get established in the soil or they may require you to treat every year. Read the label! So if I were to get a jump on them you would probably be in fall. The question still remains which plants do you treat because they are going to all look healthy even if they have these guys feeding on the roots or not.  

Q. I have taken over my desert landscape maintenance, formerly serviced by a company.  Can you please provide a general monthly schedule e.g. fertilizing, pruning, seasonal changes in watering etc. A. When I consult with people on managing their landscapes at their homes I encourage them to pay a little extra and use certified arborists for pruning ornamental trees and large shrubs. They are good at that. Only highly skilled gardeners are good at pruning fruit trees, roses and other flowering shrubs. These people are hard to find. “Blow and Go” maintenance companies should not be allowed to do any pruning on your property unless they can demonstrate that they know how to correctly prune your plants. Hedge shears are commonly used for pruning trees and shrubs, this makes them look all the same; gumdrops. Hedge shears should only be used to prune hedges. Many of these types of companies are good at pruning hedges but not other plants. I sent you a month to month calendar of operations but it’s too long to include here so I will post a more extensive list on my blog (below). Watering is the most important management practice in the desert. I discuss how to water landscape plants on my blog and some tools that would help you determine when and how much to water but water should be applied so that it wets the soil under the entire canopy of the plant. The amount of water applied is determined by plant size; large trees, water 36 inches deep, medium sized trees 24 inches deep, small trees and large shrubs 18 inches deep. Fertilizers for trees and shrubs are applied once a year in early spring and only when plants need it. Flowering plants are fertilized just before they flower and some, like roses, are also lightly fertilized three or four times per year. January, pruning and fertilizing trees and shrubs and roses, fertilize the lawn, annual flowers, vegetables and herbs as needed usually once a month. Water trees and shrubs one to three weeks apart. Apply iron fertilizers to the soil to plants that show signs of yellowing Control weeds Dormant oil application on deciduous trees February, last chance for pruning and fertilizing trees and shrubs including iron applications to the soil. Light pruning as needed Control weeds Water trees and shrubs once a week March, fertilize lawn, roses Light pruning as needed Test irrigation, make sure irrigation system is working properly for the hot months Last chance to control weeds before it gets hot Water trees and shrubs once a week April, control ants causing problems by applying an ant bait Water trees and shrubs once or maybe twice a week. May, fertilize lawn. Water trees and shrubs twice a week. June, light pruning as needed. Water trees and shrubs twice and sometimes three times a week. July, fertilize lawn at half rate of fertilizer. Water trees and shrubs three to four times a week. August, light pruning as needed. Water trees and shrubs three to four times a week. September, fertilize lawn at half rate if hot, full rate if cooler. Water trees and shrubs three times a week. October, fertilizer applications to trees and shrubs if needed. Water trees and shrubs twice a week. Control weeds now that it’s gotten cooler November, go on vacation. Water trees and shrubs twice a week. December, major pruning of large branches, dormant oil applications on trees and shrubs after leaf drop. Water trees and shrubs every one or two weeks.

  Q. Can we grow Kumquats in our area? Are they water intensive? A. Kumquats are a good choice in citrus if you want a low maintenance container plant and had had poor luck with citrus in the past. They use the same amount of water as other small citrus trees. Their mature size determines their water use. Kumquats are frequently more cold hardy than other types of citrus and provide some edible fruit that can be eaten directly from the tree.             During very cold winters it might be deciduous but generally consider the tree to be evergreen and range in height from 6 feet to 20 feet depending on which variety you choose, with a width equal to its height. Unlike Meyers lemon that flowers usually during our coldest spring weather, it flowers and produces fruit throughout the year. When to Pick the Fruit             Pick and eat the fruit when it’s bright orange because, unlike peaches and apricots but more like figs and grapes, it won’t get any sweeter after you’ve picked it. Since the peel is not bitter, just pop the whole fruit in your mouth and eat it. It does however get sweeter as the fruit gets brighter in its orange color.             Kumquat is not a desert plant, so it appreciates a reprieve from intense sunlight in the afternoon. In other words, don’t plant it where it will be in full sun or in a hot part of the landscape and don’t cover the soil in rock. Because it produces fruit and flowers, it won’t like a lot of shade either. East or North facing microclimates out of the wind are usually best. Which Kumquat to Get             Three varieties of Kumquat are popular for home landscapes and containers; ‘Meiwa”, ‘Nagami’, and ‘Fukushu’ which is a bit less cold hardy than the other two. There are some seedless selections available so look for those.

  Here are some things you can do to make your fall vegetable garden more successful in the desert.

 Landscapes are best planted during the early spring and early fall months. Sometimes they are planted when it’s hot. Learn some of the problems that you will encounter when planting out of season and why. All This and More on This Episode of Desert Horticulture.

Q. I found grubs in the soil with many established plants. Are these just a seasonal thing? How do I get rid of them now and prevent them in future? Are some plants more susceptible than others?  A. I will tell you is much as I know about them. Their adult form is a large flying beetle called a chafer or June beetle that you see in June and July. Their immature form is a white grub that feeds on dead organic matter in the soil, but I think also will chew on tender roots of plants like Lantana.             A few of them munching away on some plant roots here and there causes little plant damage. In fact, you won’t even know they are there. It’s when several feeding on the roots of one small plant, or your landscape is inundated with them that you start to see plants struggling or even dying. So, unless there is a problem I would leave them alone.             There are biological control pesticides such as bacteria (several commercial names of products available such as Grub Control) and nematodes (mostly online sales) that you can use in place of conventional insecticides like Sevin. They may take a year or two to get fully established in the soil.

Q. I have a key lime tree that’s 4 years old.  The first year it was full of fruit.  The next 2 years no fruit, then this year only 3-4 limes.  My neighbor has a regular lime tree full of fruit.  What’s wrong? A. Freezing temperatures in the spring. If you have several light freezes that go through the valley in the spring you will have no citrus fruit. If you have one freeze that goes through the valley in the spring you will have some fruit.

Q. I would like some more of your expert advice if you have time. As part of our landscape renovation completed last November, a Sago Palm and a Bay Laurel were planted. The Sago Palm is approximately 7″ in diameter and 3 feet tall while the Bay Laurel is about 4 feet tall. They both have one drip near the base and two further away with 1 GPH Emitters, They are watered for 90 minutes following the water district watering schedule for lawns this first year. Is this adequate watering and what would you recommend as the plants grow? A. If you are watering for 90 minutes then I would recommend four each, 5 gallon per hour emitters on the Sago palm placed about 12 inches from the trunk in a rectangular spacing for the first year after it is moved. The second year I would keep the same emitters but move them out to about 18 inches from the trunk. Unlike the Bay Laurel the amount of water will not change as they get taller.  Make sure the hole dug for the Sago palm is three times the width of the root ball. Make sure the soil is amended with compost at the time of planting with one shovelful of compost mixed into 2 to 3 shovelful’s of soil for the backfill. You will use this ratio of compost to soil also on the Bay Laurel. Bay Laurel Water Use The Bay Laurel is still quite small and so about 15 gallons per application is all that is needed. However, in two years you will bump that up to 30 gallons per application as the tree gets larger. Because the Bay Laurel will be a larger tree I would recommend using drip tubing coiled in a spiral around the tree instead of drip emitters. This spiral of drip tubing will be attached to the mainline spiral around the trunk of the tree and reconnected back into the mainline. Spiraling the drip tubing around the tree and reconnecting it back to the lateral will eliminate the need for flushing for that tree. If the drip tubing dead ends at the tree then the drip tubing must be flushed on a regular basis.  If you use drip tubing with 1 gallon per hour drip emitters embedded into the drip tubing every 12 inches then you will only need about 10 feet of drip tubing spiraled around the tree to give you 15 gallons of water in 90 minutes. If you use drip tubing with drip emitters spaced every 12 inches and the drip emitters emitting 1/2 gallon per hour then you will need about 20 feet of drip tubing spiraled around the tree. The spiral should be staked so that each spiral is about 12 to 18 inches apart around the tree.  Personally I would use the 1 gallon per hour drip tubing with emitters spaced 12 inches apart. It’s very easy to come by locally. As the tree gets larger every two or three years you will splice in another spiral of drip tubing To give it more water because it’s larger.

Q. I reached out to you a couple of years ago regarding the lime and lemon trees we planted about three years ago.  Here they are, both are filling out and growing taller.  My question is why no fruit?  This year we had two tiny limes and no lemons.  We follow fertilizer instructions. The tag on the lemon and lime trees stated pollination not required.  I understood that bees are not required.  We do not recall a freeze last spring.   A. Citrus of all forms does not grow well in the Las Vegas Valley. You will have good years and bad years. If there are freezing temperatures in the spring you will have spotty production of fruit. If it’s a warm spring with no freezing temperatures than you will have good fruit set if you saw flowers. If you saw no flowers, there will be no fruit.  All Fruit Trees Need Bees When you see flowers make sure that you see some honeybees. To attract honeybees to your yard plant some rosemary or other herbs that flower during the winter time that attract honeybees. Put out a tray of water and change the water weekly to keep it clean. Water will also attract honeybees but flowering plants in the winter that they like are better. Las Vegas is Not Known for Citrus Production. Why? FYI if we didn’t have freezing temperatures here there could be a vibrant citrus production area. That production area in the desert occurs in Yuma where it’s less likely to freeze in the spring. Winter temperatures in Yuma, Arizona, are warmer than they are in Las Vegas. Citrus are subtropical. Any fruit trees that produce flowers before freezing temperatures are finished are likely to not produce fruit. That’s true for peaches, apricots, nectarines, plums. It’s a basic rule of fruit science. Pollenator vs Pollenizer Saying that the trees don’t require pollination means that they don’t require another tree to make fruit. They will still need honeybees as pollenizers not pollinators. Pollenizers are insects. Pollinators are other trees. Freezing Temps Can Happen at Sunrise Had one freeze that came through this past spring. It’s very easy to miss if you’re not looking for it. The coldest temperatures are just before sunrise. After sunrise the temperatures get warmer. Use an inexpensive low temperature thermometer and check for yourself.

 Summer heat can be brutal on plants. Maybe it isn’t always the heat.