Bugs are on the Attack; Fruit Trees and Vegetables

Many questions sent to me right now are about bugs appearing on fruit trees and vegetables. Remember, never apply sprays of any sort while fruit trees are blooming. My first recommendations for pest control are natural or organic spray remedies. If my recommendations are not natural or organic, I will tell you they are conventional spray remedies.

Yes, it will cost you more money but always use a wetting agent combined with any sprays used for controlling insects, diseases and weeds. A wetting agent is not needed when applying insecticidal soap sprays. Soap sprays can be combined with other insecticides and act as a substitute for a wetting agent.

Insecticidal soap commercial size

            Big problems right now are aphids on all fruit trees as well is young vegetable transplants. Aphids inhabit the undersides of leaves where it is darker and less obvious to their predators. Aphids are now feeding, colonizing and building their populations exponentially. They are sucking plant juices from the leaves and excreting a sweet, sticky substance called honeydew.

Apricot leaves with aphid honeydew

            Soon aphids will attract ants that collect this honeydew. Ants then climb the tree in long, continuous rows that go back and forth from the aphids to their nest which is usually in the ground. Many people will try to control the ants but ignore the aphids. To control ants, control the aphids.

Aphids and ants together with aphids only there due to the presence of aphids

Soap and water sprays are very effective if sprayed directly on the aphids. Please use either a commercial insecticidal soap or an unscented liquid detergent that contains no hand care products. I prefer a liquid Castile soap for insect control but it can be more expensive than purchasing and insecticidal soap. Some people use Dr. Bonners.

Aphids and ants on the same apricot leaves

Horticultural oils are also effective and can be safely used after bloom and until temperatures reach about 85° F. Horticultural oils are refined mineral oils. Neem oil is an oil spray and can be used as a substitute for horticultural oils if you choose.

Horticultural oil commercial size

If you have nectarine, Western flower thrips are likely attacking the fruit right now. They have been attacking the flowers even before they were open. These tiny winged insects are poor flyers but able to go the short distances between fruit and attack them, ripping at the skin of the fruit causing it to “bleed” sap which they use as food. The ripping of the skin causes it to scab, become deformed and ugly. Western flower thrips are responsible for the ugly, deformed appearance of nectarine fruit.

Thrips damage to immature apricot

Spray the fruit now with an insecticide containing Spinosad listed in the ingredients. Direct your sprays primarily at the fruit because that’s what you are protecting.

One spray application of Spinosad is not be enough to protect the fruit from scarring. You must spray it multiple times as the fruit is developing if you want it unscarred. Alternate Spinosad sprays with soap and oil sprays weekly.

Mulch Can Create Problems for Peach Trees

Q. I bought a Babcock peach in the summer of 2014 and planted it at about an elevation of 3700 feet. I planted it as you recommended including a 4 inch layer of mulch on top of the soil around the tree. The tree budded nicely but I noticed most stem ends just died and dried up this past winter.

Two-year-old Babcock peach

Dieback on Babcock peach stems from a lack of water

A. When stems die back like you describe it is usually a problem with water or freezing temperatures. Unless temperatures dropped down to 15° F it is most likely water related.

            Water related can mean either too much or too little water because both can result in stems dying back. It is obvious that a lack of water can cause something like this but less obvious if it is from too much applied water .

            Giving a plant too much water can mean either two things; either applying too much water each time you irrigate or giving the plant water too frequently. The first one, applying too much water each time you irrigate, usually doesn’t create a problem for the plant, it just wastes water. But the second one, watering too often, can be far more dangerous to a plant.

Collar rot or crown rot on honeysuckle because of wet mulch in contact with the stems

            Watering too often can fill the soil around the roots with so much water that the roots cannot “breathe” and they begin to suffocate. Allowing the water enough time to drain from around the roots allows air to enter the soil again and roots can breathe.

            Unless a plant is growing in pure sand or in a small container, withholding water for a few days before the next irrigation gives roots a chance to “breathe” again. There is enough water left in the soil to last a few days after an irrigation in normal soils.

Apple growing in wet soils with collar rot

            There is another possibility. You mentioned you have a 4 inch layer of mulch on top of the soil surrounding the tree. This will really help your trees, however do not allow this mulch to rest against the trunk of new trees. Always keep mulch away from the trunk of trees while they are young. At least 12 inches.

Wet mulch can “rot” the trunk where it is in contact with the wet mulch. This “rot” is a disease called collar rot. Collar rot disease will “choke” the trunk and prevent water from moving from the roots to the top of the tree. The symptoms are identical to a lack of water and this is a strong possibility in your case.

After Agave Blooms It Will Die

Q. I bought this plant 4 years ago and was told it is an Octopus agave. I was advised it might take 40 to 50 years to bloom and afterwards the plant will die. The stalk coming from the center of the plant grew to about 12 feet in 2 weeks. I really do not know what I am looking at or what to do.

A. This is not Octopus agave. Compare it to pictures of Octopus agave on the Internet. Yes, that is a bloom spike. The plant will die after it flowers.

The mother plant should have small offsets or pups at the base of the plant prior to blooming. You may not see them until after the mother plant dies and is removed. These pups can be replanted in new locations or given away to friends.

Pups growing at the base of American agave.

When planting agaves and cacti, amend the soil with compost at the time of planting and mixed with the backfill around the roots. They will grow better.

Be careful how frequently the plant is watered. Do not water them more often than every three weeks but give them 5 to 10 gallons when you do.

Some information on Octopus agave from Master Gardeners at the University of Arizona

Agaves look better when they are either planted in groupings of three or five with enough distance between them so they can spread out or planted singularly as a focal point in the landscape.

When planting in groups, use odd numbers of plants and plant them at different distances apart to make them more appealing to the eye.

Plant Irish Potatoes Now

Q. Do Red Pontiac potatoes grow in Las Vegas? When should I plant them?

A. Red Pontiac potato is an excellent variety for Southern Nevada and Irish potatoes should be planted now. It is best to purchase certified potato seed (potato seed are potatoes cut up into pieces that have “scabbed” over or healed slightly) for planting. 

Many gardeners buy potatoes out of the grocery store, cut them into their own pieces and plant them. It can be done but the problems faced are virus diseases in the tubers because they are not certified and buying potatoes treated with chemical sprout inhibitors. Sprout inhibitors cause them to be really slow in sprouting after planting.

Potatoes growing with drip irrigation

Cutting a potato into seed pieces is quite easy. On smaller potato tubers, cut them into equal sized quarter pieces, let the cuts heal at room temperature for 24 hours and then plant them. Large potato tubers are cut into six pieces. Each piece should contain an at least one "eye" and plenty of flesh around it. 

Potatoes growing in North Las Vegas Nevada

Plant them directly into the prepared garden soil or put "seeds" into a shallow flat that drains easily and cover them with soil. Watering them in a flat at warm temperatures causes them to "sprout" in a few days. Once they have sprouted, carefully plant them in the garden about three or 4 inches deep and 12 inches apart in rows. Be careful not to knock off the sprouts from the pieces when you're planting. 

In large gardens rows are about 3 feet apart. In raised beds you can squeeze potatoes in rows closer than this but alternate them in the rows so they have more room to grow. Once the potatoes are about 12 inches above the soil cover the potato plants with loose soil so that only a couple of inches see light. 

Potato tuber growing on short rhizomes from mother potato plant

Potato tubers form on short rhizomes growing from the stems that are buried in soil. As the potatoes plants grow more, cover the stems with more soil about every three weeks. Feed them with nitrogen fertilizer lightly about every four weeks. Do not let them stress from a lack of water until you are ready to harvest. 

If you plant now, they should be ready to harvest in about July. Cut back on the water at this time so that the skins of the potato begin to heal. There are plenty of other varieties to try including Yukon Gold, Russets, blue potatoes and fingerlings.