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Friday, July 29, 2016

Apricot Disease Seldom Occurs in the Desert

Q. My apricots were doing very well as they have for the last several years.  After thinning a large crop this year, they were growing very well and appeared to be getting ready to pick when I opened the cots, I found the insides to be rotting.  I've tried to do a little research without success. 

A. This may be ripe fruit rot, sometimes called Brown fruit rot. It can happen if there is rain near the time of harvest. We get other diseases on fruit as well if there are rainy periods at different stages of fruit development.
            There is not much you can do except hope that rain does not occur at that time. Here is some information from the University of California. See if this description matches your problem.

They recommend fungicide applications earlier in the season to present it but we get such a little chance of rain here to me it doesn't make any sense to make these applications. Just figure this year you had some losses that come along very infrequently.

Citrus Help For the Land of Ice and Snow

Q. I live in Michigan, so our experience with citrus is non-existent, and there are no experts in our area, but you come recommended as someone who might be able to give me some advice. 
I have a small potted orange tree with a few leaves that have turned light colored along the edges.  They aren’t yellow or brittle as one might expect in the case of iron deficiency, but are shiny and flexible like the rest of the leaves.

I bought the tree on a lark, never expecting it to survive, but it thrives except for these few leaves.

The plant is outside, on the east side of the house when the temperatures will stay about 40ºF.  The rest of the time (about 7 months a year) it is inside, on an east facing but brightly lit porch.  It has never been frosted.

The tree has been potted for 2 ½ years.  I have not re-potted it.  It is about 14” tall.  It was originally potted in soil that was 50% commercially prepared potting soil and 50% composted leaves.

Our water is very alkaline, so during the winter I water with black tea, made with distilled water and fertilize at about half strength with Miracle Grow.  During the summer I water with rainwater and fertilize with the rest of my plants, again using Miracle Grow, this time at recommended strength.

Have you any suggestions for me?  Any advice would be appreciated.

A. It will be fun for you to grow a citrus in Michigan. I am originally from Wisconsin so I can understand your interest in having a citrus growing in Michigan. First of all make sure the container is large enough for your tree. It will need to be fairly large.

Secondly the tree should be removed from the container every 2 to 3 years and wash some of the soil away from the roots. Cut off some of the roots near the outer edges and repot the citrus in the container using new potting soil. In two or three years the organic matter content of the soil in a container will be gone. The soil would become more compact and the roots of the tree will begin to suffocate. Water will not flow through the container as easily as before. The air spaces around the roots collapse. Root rot begins to set in and this usually causes leaves to start scorching on the edges, yellowing and falling from the tree. Repotting the tree every 2 to 3 years and trimming off some of the excess roots helps to keep the tree young and vigorous. Using new soil increases the air spaces around the roots and helps keep them healthy. When you take the tree out of the container, look at the roots. Healthy roots are creamy white. Roots that are beginning to die turn brown.

When you repot the citrus also reduce the size of the canopy or top of the tree. Look at stems that are too close together or on top of each other and remove them totally. Avoid giving the tree a "Butch haircut". You will generally thin out the branches and open the canopy. If some of the limbs are too long, cut them back so they are shorter and reshape the tree.

Leave the citrus out in the container outside as many months as you possibly can during the spring, summer and fall. They can take reduced sunlight for maybe two or three months but no longer than this. It sounds like to me you are keeping them inside too long. If you have a warm spell during the winter when it's not freezing, put it outside and let it get lots of sunlight. The tree will store this energy inside of its trunk and limbs and live off of it for a time when light level is low and inside the home. If you can put a florescent light close to it, a few inches away, leave it on for 12 to 14 hours or longer each day when it's inside. This will help a lot.

A common problem on citrus are scale insects, usually brown scale. Look for these brown bumps on leaves and stems. If you find them, use a horticultural oil and spray the leaves and stems with it about once a month and you will start to see the populations of this insect decrease. Brown scale and root rot because of watering too often or poor drainage and a lack of sunlight are the worst problems.

Insects on Fruit Easy to Control Without Pesticides. Just Clean Up!

Q. Could you tell me what these little buggars are and how to eliminate them?

A.  This is not a common pest of fruit. It is an insect that just happened to be in the area and found something it could eat, had more of its own and decided you had a place it could set up residence. 

I am not an entomologist but know enough that I could identify it if it was a common pest. It is not. At first I thought it was a sap beetle but it is not. 

Regardless, the control is the same. Pick up and dispose of all damaged fruit on fruit trees and the ground. Compost them or get rid of them. Once you get rid of their food supply (damaged fruit) they will begin to disappear. 

From the look of them they do not have the ability to damage fruit themselves (their mouths cannot chew things) they look for already damaged fruit so they can feed and multiply.

Some Bees are Stingless to Humans

Q. I noticed numerous several small bees swarming around one of my brick planters.  The bees were not aggressive and small … about ½ to ¾ inches long.  There wasn’t a hive of any type, but I did notice a small hole (about ¼ in diameter) in the dirt where the bees would enter and exit.   I did some quick internet research and these appear to be type of Solitary Bee.  Attached are two pics of one that I caught with my pool net…sorry the pictures aren’t very good, but I was hoping that you could confirm that these are Solitary Bees.  They have a black/gray body and the underside is yellow.
If they are Solitary Bees, the research I did indicates that they aren’t aggressive, rarely sting, and are great pollinators.  However, they are a nuisance where they are located.  Do you have any suggestions on how I can get them to move ground nest to another location without killing them?
One of the solitary bees we frequently see signs of in the garden include the leaf cutter bee.
You can build bee boxes or homes for these bees to use for egg laying by drilling one 2:45 eighths inch holes deeply in large blocks of wood.
A. Joe yes these are solitary bees. I am no be expert but my understanding is that solitary bees do
not make be colonies, they do not make sizable amounts of honey, they are not aggressive and they cannot sting. However, I think they get a late start in the season and so early crops such as tree fruits may not be the best for them to pollinate. They are better for pollinating plants that bloom later in the season like summer vegetables and flowers. 

An example of a solitary bee are the leaf cutter bees. You can attract more bees by putting out clean water. They need water to keep cool, honeybees in particular to cool their hives. Honeybees are constantly carrying water back to the hive during hot weather. But the water has to be changed regularly. 

As far as moving them, I don't know any way to move them. I think many of them lay their eggs in these holes and the young bees emerge from them later. That is the way with leaf cutter bees so I'm guessing these guys are similar.

White Flufffy Insects Common Problem on Many Cacti

Q. I appear to have a massive infestation of Cottony Cochineal Scale on my prickly pear cactus. I can usually get most of it off by hosing, but much is hard to reach. Beyond hosing, what insecticide or other kind of solutions do you recommend? Permanent, if possible!

A. Yes, scale is quite common on cacti in general and prickly pear in particular. This one in particular is most likely cochineal scale rather than cottony cushion scale. This cochineal scale is a close relative of the cochineal scale that was used by the Spaniards in Mexico centuries ago and die making. This scale leaves a purple color on your finger when you rub it.They can be hosed off the pads with a strong stream of water as you are doing but they reinfest the pads very quickly and in full force again in a week or two.
            When I am growing prickly pear as a food I am more concerned with insecticides and getting them into the food we eat but if they are grown just as an ornamental plant and not used for food then I feel better about using something stronger than water, soap and water sprays.
            The problem with a strong stream of water is that the force from this water is not enough to knock the insect off of the pad, only the white, fluffy coating surrounding the insect. So it is a short time before it regrows this protective cover and the unsightly mass of cotton is back again.
            Knocking the fluffy covering off first with a strong stream of water will make these insects more susceptible to an insecticide spray. Most of the common insecticides will work after that; malathion, pyrethrins, Sevin, just about any common insecticide will work after the fluffy covering has been removed. This does not mean they won’t be back. They will. But it will take longer for them to get established on the plant again.

Grapevine Had No Grapes for Two Years

Q. My grapevine had grapes for the first of four years but this and last year it had none. What is wrong with my grape vine? By all appearances it looks perfectly healthy but it didn’t produce grapes for the last two years.

A. The fruit or berries of grapevines are produced only on the wood which grew the previous year. Growth this season and three-year-old wood and older will not produce any fruit. Two-year-old wood is the only place that can produce flowers and fruit.
If all of the two-year-old wood is removed or dies, there will be no flowers or fruit. If the vine is left to grow without any pruning it will produce lots of fruit. But over the years this tangle of growth will create problems from crowding, fruit rots, disease, and it will be difficult to harvest the fruit.
Next spring do not prune. Let the vine grow. At least this way you will get some fruit from it. Your other option is to learn how to prune grapes correctly.

Figs Not Ripening

Q. We have two fig trees loaded with figs. Problem is they are not ripening. What is our problem or do they take a long time to ripen?

A. Most of the main crop of figs is still green in June and have developed to maturity. If the tree is getting plenty of water, the figs should be enlarging rapidly. If the figs are not enlarging, then the tree is not getting enough water.

Figs that produce fruit need a lot of water so that the fruit will enlarge. If you don't give the tree enough water the fruit will stay small and fall from the tree, hard as rocks.

Keep Irrigation Water Off of Plant Leaves to Reduce Powdery Mildew

Q. I have powdery mildew on lower branches on my shrubs. Should I remove the dying leaves? Since the temperature will be 114 tomorrow, should I wait until Fall?
Powdery mildew on Japanese euonymous. These plants are famous for mildew.

A. Powdery mildew on these plants is probably left over from this wet spring. Powdery mildew disease does not require high humidity. As far as diseases go, it probably has the lowest requirement for humidity or moisture.
            The usual reasons for powdery mildew besides cloudy, rainy weather is shade, poor air circulation and poor plant health. If you can reduce the shade with some light pruning that may help.
Make sure there is no splashing water from an irrigation system. This will spread the disease from leaf to leaf or plant to plant.
Sulfur dusts as well as neem oil have been known to work as preventive sprays. Otherwise use traditional fungicides that list powdery mildew control on the label. But with these high temperatures the disease should subside. It is a cool temperature disease.
If the leaves look pretty bad, then go ahead and remove them. At least then you are removing disease inoculum. But consider some light pruning instead. You won't hurt anything with light pruning this time of year and you may give the lower parts of the canopy more sunlight.

Small Round Holes in Tomatoes is Tomato Fruitworm

Q. I found about 4 to 5 tomatoes with holes in them. I have been getting ripe tomatoes for about 30 days and found these with holes in them during the last two days. I searched for bugs, eggs and leaf damage but did not find anything. Any ideas?
Probably tomato fruitworm damage

A. The 3/8-inch diameter and larger holes in your tomatoes look like damage from the tomato fruit worm. These are worms, or caterpillars, are about an inch and a half long and 3/8 of an inch wide. They eat holes mostly in tomato fruit, usually when they are green or when they turn red but are still hard or firm. Frequently the fruit becomes rotten from these holes.

Organic sprays of Bt or Spinosad when the fruits are starting to form will prevent this.

Saguaro Should "Rest" Between Irrigations

Q. We have a concern about our Saguaro planted in 1988. It now has three large arms and we recently noticed a crack on the outside of one arm at the bend of the “elbow”.
Saguaro growing near Parker, Arizona

A. Don't water it too often. Watering about 10 or 15 gallons around the base of the plant in a 5 to 6 ft radius once a month is enough. Those plants expand like an expanding accordion when they swell up with water.

Let them use this water before you give them another drink. The plants will shrink in size when they use their internal water supply. If they are given water too often they can swell up and split. The splitting may have happened during the rains this spring and early summer. Regardless, the crack should heal and give the plant a little bit of character.

Watering Saquaro

Q. I have a healthy Yucca tree (10 years old) in my desert landscaped yard (similar but smaller to what is pictured below). The homeowner before me watered it daily in summer and weekly in winter along with the rest of the drought-resistant plants in the yard and did so for many, many years. I have continued that practice but have read that Yuccas should not have daily watering. Since everything looks healthy and vibrant, would it be OK to continue daily watering in summer? Thanks.

A. Exactly right. They are not supposed to be watered this way. However it appears the previous owner found a happy medium between watering frequently and not watering too much. My guess is the tree was getting very small amounts of water daily. 

I would not worry about it if the plants are doing okay and I wouldn't change anything. However, you should be aware that you are doing it entirely wrong but it's working. Be careful if you change anything because these plants are now adjusted to that watering schedule.

Forcing Bougainvillea to Be More Vigorous

Q. I am concerned about one of my three Bougainvillea plants growing on the south side.  I removed some very old and scraggly oleanders from this spot and raked out all the oleander leaves before planting these Bougainvillea.  I feed them and they have good water supply, but the one in the center is scrappy looking while its brothers on either side are thriving. 
Bougainvillea grown as a woody perennials shrub in Bullhead city, Arizona where it seldom freezes.

A. Bougainvillea do very well here during our summer heat with a minimal amount of care as long as the soil is amended at the time of planting and they are fed regularly with low nitrogen fertilizers.
They like to be pruned so if you see them struggling, prune them back, give them water and fertilize them lightly with a rose or tomato fertilizer.
They also bloom better if they are struggling rather than if they are pampered too much. Going through a dry period may encourage blooming.