Iron chlorosis in Indian hawthorne due to poor soil development from lack of organic decomposition of rock mulch. Q. Following your advice, I am planning to replace all of the stone mulch under and around the existing shrubs in my yard and replace with bark mulch from the orchard stock pile. I have been told that bark mulch attracts cock roaches. Is this your experience? A. Wood mulch will attract quite a number of animals and foster plants that contribute to the breakdown of the mulch and roaches do contribute to that. These include mushrooms, earthworms, larvae of beetles such as grubs, gnats, and others. Mulches that decompose will attract decomposers.Roaches tend to congregate in irrigation boxes in the landscape and these should be treated periodically for control if this is a problem. I normally tell people to keep the wood mulch a couple of feet from the foundation of the house.Rock mulch will give you a more “sterile” environment and if that is what you prefer then stick with rock mulch. There is nothing wrong with rock mulch if it is used with plants that can tolerate rock mulch such as most desert dwelling plants. However, decomposing wood mulch has many, many advantages for plants compared to rock mulch which adds nothing back to the soil and most plants will perform better with wood mulches. If you would like a copy of the benefits I can forward this information to you or any of my readers.

Mexican papaya in containerQ. I saved some papaya seeds last year and planted three of them in the spring. To my surprise all three began to grow. It’s hard to tell but the three plants are different sizes. I’d like to transplant them into individual 15 gallon pots. I read where they do not like to be disturbed once they start growing. What might be the right time to attempt that? Meanwhile I need to keep them somewhere once it gets cold outside. What would be the best way to keep them through the winter? And what are the chances they would ever bear fruit some day? A. Master Gardeners who attend my classes are very familiar with me saying, “You can grow any plant in the world in Las Vegas. It depends on how much time, energy and money you want to use to make it happen.” Rare fruit growers in Phoenix grow papayas outside with some freeze protection applied during the coldest part of the winter. We are not Phoenix but we do have some similarities.This is what you need to know about papayas to be successful. Papayas prefer rich, tropical, acidic soils. They will not withstand temperatures much below 32F or freezing. Papayas do not like direct sunlight from the late afternoon sun and would prefer about 30% shade if in full sun. Papayas will die growing in soils that do not drain easily but also do not tolerate dry soils.They are heavy feeders and so require continual applications of small amounts of fertilizer. They need both male and female flowers to set fruit. Sometimes this happens on a single plant and other times it requires a male and female plant. So plant several so that your chances of getting male flowers is increased.They are normally started from seed and, as you found out, the seed germinates easily. Most of our papayas come from Mexico due to costs of production. They should transplant fairly easily into 15 gallon containers if you are careful and stake it in the new container to keep it upright and wind resistant.Keep them lightly shaded until the roots have reestablished in the container, maybe one month. They should be able to handle more sunlight after this. Some varieties of these plants may become damaged anytime the temperature reaches about 45° F, others are more resistant to this type of chilling injury. They will not handle any freezing temperatures at all and they become stunted at temperatures even slightly above this. I have no experience growing them here but it’s reasonable to assume that they would handle morning to mid afternoon sunlight but not late afternoon. They will handle some light shade but will probably not do well in fruiting if the shade is too much.These trees produce at a very young age, some produce at a younger age than others but they are also very short lived. Of course it would be best if they were in a greenhouse here and handled as a tropical plant.No one is certain how the fruit is set; whether it is by wind or by pollinators. If you’re lucky enough to keep it long enough to get flowers you may have to do some hand pollination if you do not get fruit set. Your biggest challenge will be to keep it from getting hurt during the winter and still provide enough light during the summer to encourage flowering and fruit set.

Q. I have a nice little compost pile that is about ready to spread. I read where fall is the best time to spread compost around fruit trees. Is that true? Composting wine grapes at the Orchard A. We do use compost around some of our fruit trees at the orchard. The fruit trees I like for applying compost are persimmon, Asian pear, and other fruit trees that have not originated in arid or desert climates.All of the fruit trees will benefit from an application of compost, even grapes. If you grow any blackberries or other cane fruit they will benefit as well. I usually spread compost around the fruit trees just prior to spring growth in mid January for the earliest. I will still supplement it with iron chelate. It needs two or three weeks of irrigation to begin moving the nutrients from the compost into the root zone and into the tree.

Agave weevil in agave crown Q. I have a question regarding ‘grubs’. We lived in Texas where we had grass and were accustomed to grubs, but we are experiencing them here. We were dumbfounded and unprepared for grubs in the desert. We have lost several very mature cacti to grubs. I purchased grub control chemicals and have followed instructions but still seem to have them. Is it normal to have grubs here? Are there specific plants they zero in on? Can you recommend what we should use? A. There are many different types of grubs so when we speak of grubs we have to be certain about which grubs we are referring to. Commonly we find grubs in lawns (white grubs, aetenuis beetles), in compost or decaying organic matter (June bugs), grubs in some cacti such as agave (agave weevils), and others. Green June beetle life cycle In cacti it is usually the agave weevil which prefers agaves to other types of cacti or succulents. This frequently requires a pesticide drench over the top of the plant and drenching the rosette about three times; once each in April, May and June according to some growers in Arizona. The liquid is preferred for drenching.Granular pesticides can be used but must be watered in around the plant and should be a systemic approved for grub control and applied about the same time as the liquid drench. The liquid drench has the advantage of killing newly hatched grubs from eggs laid in the bottom of the leaves in the rosette.

Basil Growing in the hot Las Vegas Valley of the Mojave Desert Nothing is worse than harvesting herbs and eggplant and by the time you get them in the door they are withered or soft and no longer firm. Or your products didn’t last very long in their cooler. Here are some suggestions on how to harvest these tender plants from the garden and keep them fresh. The ideal time to harvest most herbs is as early in the morning as possible. This is the time of day when temperatures are lowest, humidity is highest and winds are low. This is also the time for herbs when those volatile oils that are so important are at their peak and flavors are best. Harvesting should be at a time when the flower buds are just starting to form but before they open. When the flowering cycle begins, the plant begins to shove nutrients at the flowers and subsequent seeds which takes precedence over the production of leaves and stems. Flower formation indicates this loss of nutrients in leaves and stems is about to happen. After some familiarity you will begin to visually predict when this occurs as you note changes in the growth of the plant. If at all possible, spray herbs and soft vegetables with a mist of water 10 to 20 minutes before harvesting to wash dirt from the surface, cool the plant down and rehydrate the surface. Check with your local ordinances to make sure this is permissable prior to sale if you are selling. In the case of vegetables, the larger the vegetables the longer it takes to cool the plant down. So don’t expect that a quick rinse of eggplant for instance to have much impact in cooling the fruit down internally. In our dry climate the cooling effect from spraying a plant down with water may last ten minutes at best and then the temperature begins to climb back toward the air temperature quickly. On the contrary, a light mist of water on the surface of most delicate herbs and leafy vegetables will cool the plants down considerably. Make sure you take a clean bucket with cool, clean water (nonchlorinated would be best) into the field with you. During summer months the water temperature should be at least cool to the touch and cooler than the air temperature. For those requiring more exacting guidelines you should have temperatures about 55 to 65 F. There are some plants that can be packed in ice while others cannot. Icing is usually reserved for cold hardier plants like broccoli, spinach, cilantro, parsley, green onions, and Brussels sprouts. Icing more tender plants will result in injury. The four major enemies to plant quality and storage life occur after harvest: damage from handling, low humidity and water loss, high temperatures, and direct sunlight. Do everything you can to keep these enemies from damaging your harvest. Damage from handling. Harvesting requires a sharp and sterile knife or shears. Herbs and soft vegetables should be severed from the plant cleanly without tearing or ripping and lifted rather than pulled and immediately immersed in clean, cool water. Any surface tearing or scarring impacts the quality of herbs and soft vegetables and their storage life. If you have long fingernails or wear jewelry on your hands that could tear or rip, wear thin plastic gloves to protect these tender plant parts from damage. This may sound like these precautions are “overboard” but if you expect to store these plant parts for any length of time, damage to the surface of the plant allows water to be lost and disease pathogens entrance. All herbs and soft vegetables have to be inspected for damage and sorted for quality. Sorting or grading of products, if not done carefully and out of harsh conditions, can intensify damage and result in even more losses. Low humidity and water loss. Our desert climate is naturally low in humidity. That is great for growing plants but not so after harvesting. As soon as the herbs or vegetables are severed from the plant its source of water is removed, air enters the stems, water no longer moves through the severed plant part. Plants with roots attached can lose water from leaf and stem surfaces and water from the roots replenishes lost water. This keeps the leaves and stems hydrated and cool. Evaporation of water from leaves and stems helps cool the plant. As water is lost from severed plant parts their freshness and quality is compromised. Immersing them in cool, clean water immediately after harvest helps keep these products hydrated and fresh. Keep these plant parts out of the wind, direct sunlight and high temperatures which drive excessive water loss. High temperatures. It should go without much explanation that harvested plant parts should be kept cool unless you are dealing with vegetables that require high temperature and humidity after harvest such as sweet potatoes. Direct sunlight. The energy from the sun can be deceivingly destructive. I don’t know how many times I have told people in the field to put harvested products in the shade, even if it is under the shade of other plants. This is one of the most commonly abused practices after harvest. I observed small-scale producers in Kenya on the slopes of Mt. Kenya harvesting products and putting them in direct sunlight to be picked up by the co-op truck a few hours later. To top it all, these products were sorted and graded at the co-op headquarters by co-op members in DIRECT SUNLIGHT! Coop members then did not understand why half or more of their harvest was rejected by the exporter. Cleaning. A light salt solution (two tbs per five gallons or 35 g. per 20 L) can clean products of insects without damaging plant parts. Straight table salt, sodium chloride, has two chemicals that can cause plant damage; sodium and chloride ions. If too intense, damage will result. A better salt might be a potassium