Cold, not wind, most likely source of blossom loss

Q: I am writing you in regards to a problem I'm having with my fruit trees . I have a tree that grows five kinds of citrus fruit: Pink Lemonade, Bearss lime and three varieties of orange (Washington navel, Honey Mandarin and Valencia). I also have two other trees, a lemon and an orange, but do not know their variety. My problem is the wind that causes them to lose their blossoms, which then causes them not to bear fruit. These trees are planted near the south wall in my backyard. What it the best way to prevent the loss of the blossoms in the spring due to wind?

A: I do not believe that wind is blowing the flowers off of your trees. In order for that to happen, you would need gale force winds. It is more likely that there was a dip in temperature causing a little bit of freezing damage.

All of these trees you mentioned cannot withstand cold temperatures. Just the slightest freezing temperatures will nip them and cause them not to flower or drop their flowers. The most cold tolerant in the group is probably the Pink Lemonade, which is most likely Eureka lemon that may withstand 26 F.

All of these trees must be in a warm microclimate if they are to produce any fruit in the Las Vegas Valley.  And even if you have a warm microclimate, the chances of production will be iffy due to late spring freezes.

The best advice I can give you is to provide some type of wind barrier to the area of the yard where they are planted. Wind combined with low temperatures can make freezing damage worse in the spring.

Q: We have a pomegranate tree which grows fruit, but not to the size of those that sell in stores or larger. They are very small. This tree is growing on a slight hill and gets watered for about 20 to 30 minutes a day, plus my wife gives it an additional 2 gallons of water almost every day during the summer months. What can I do to get larger fruit and more of it?

A: Increasing the size of your pomegranates is more about pruning, watering and fertilizing than anything else. Larger fruit will be produced on older wood so pruning a pomegranate to be more like a tree than a shrub will help.

During fruit formation it is very important to make sure pomegranate receives adequate water. Water shortages during fruit development will result in smaller fruit at maturity or split fruit before it matures. Irrigations should not be daily; water should be applied in larger quantities but less often.

Fertilize pomegranates lightly or in moderate amounts in February. More fertilizer does not translate to more or larger fruit. But adequate amounts of fertilizer will. Mulching with organic mulch around the tree will help.

Q: I know that this is not the time of year to fertilize plants, but I have a few questions . Do you have any suggestions for a good way to apply fertilizer to plants that are in rock mulch? It's somewhat of a hassle to move the rock from around the plants, apply granular fertilizer, work it into the soil, and then replace the rock. I've used Miracle-Gro for foliar feeding, but they recommend that you feed the plants every seven to 14 days. Is there another liquid option that only needs to be applied once or twice a season?

A: Let's cover a few options that you can use to fertilize plants in rock mulch.

The liquid drench method. You can take a fertilizer that is water soluble, dissolve it in a bucket of water and apply it to the root area where it is irrigated.

The dry fertilizer drench. Apply a dry fertilizer to the rock mulch between the plant and its source of water. Take a hose with a nozzle and wash it into the mulch.

The fertilizer stake method. Take fertilizer stakes and either push them or hammer them into the soil after an irrigation in the area close to the source of water. Of course, you will use the plastic cap that comes with the stakes when you hammer them into the soil.

Foliar applications of fertilizer. This works quite well but as you mentioned it is short-lived compared to a soil application. Make sure you use a wetting agent with the foliar spray.

Install a fertilizer injector. These can be very pricey. Remember that with an injector the fertilizer is applied in proportion to the amount of water that is given to a plant. It is important to have an irrigation system that applies to water correctly if this is to work well.

Q: My tree is 30-feet-by-25-feet and it is in a lawn area. We follow the Southern Nevada Water Authority guidelines for watering our lawn. Very little dieback has occurred on this tree, and the only fertilizer it gets is what it steals from the lawn.

A: Unless you are overwatering, watering enough for a lawn is not enough for a tree planted in the lawn. Watering a lawn is enough for the lawn only.

When you put a large tree on it, then you must deep water the tree as well as water the lawn. The only time trees do well in lawns is when the lawns are overwatered .

As the price of water has gone up, people have chosen to conserve more and follow lawn-watering guides more closely. This has caused some trees to be underwatered.

Lawns are big fertilizer hogs, particularly of nitrogen. If you apply fertilizer to the lawn, then the lawn will get the fertilizer due to its extensive fibrous root system. Trees should be fertilized separately with applications in the root zone, which is just below the root zone of the lawn so that the lawn does not burn.

You can judge if the tree is growing enough by looking at its new growth this past year. It will be a different color than the older wood. On a tree that size you should get 12 or more inches of new growth each year. If not, then something is wrong. It might be a lack of water, a lack of fertilizer or both.

I don't know the type of tree you have but if you have Modesto ash, make sure you do not have Modesto ash decline. A picture of Modesto ash decline is posted it on my blog. It is common here but does not hit every tree. I have been working with this problem for more than 25 years with other professionals and no one has been able to determine its cause. This is why I no longer recommend this particular ash tree.

Bob Morris is a horticulture expert living in Las Vegas. Visit his blog at xtremehorticulture.blogspot.com.