If you have fruit trees, the next big tree management activity you are facing is fruit thinning or removing excessive amounts of fruit so that the remaining fruit gets larger. Peaches, nectarines, plums, apples and pears must have excessive fruit removed if you want larger fruit. Do this as soon as the fruit reaches the size of your thumbnail.
With peaches and nectarines, space the fruit about 4 inches apart. With apples and dessert pears like Bartlett, the fruit grows in clusters. Remove all but one fruit from each cluster, leaving behind usually the largest in the cluster. If there aren’t that many clusters, then leave two per cluster.
Plums are easier to thin than you might think. But you should wait a little bit because some of the plums will be knocked off by strong winds or become yellow because of lack of pollination. These small fruits will drop from the trees.
Thin the remaining fruit by massaging large groups of the fruit with your fingers. Alternatively, you can use a stick or piece of PVC pipe and gently rap the limbs until the remaining fruit is far enough apart.
I don’t typically thin the early apricots unless they are growing in tight clusters. If there is a great enough distance between the fruit, I leave them alone. If the fruit is growing in tight clusters, I massage these large clusters with my fingers until I reach a density that I like. This requires practice and experimentation on your part.
Usually, there is not that much of an advantage by thinning figs, cherries and pomegranates.
If you need help or some practice, take my fruit thinning classes April 18 and 19, which are offered on Eventbrite, and we will discuss it and practice it in the orchard.
Q: I recently moved into a house that already had apple and cherry trees growing. I don’t know which ones they are, but each year the apples develop some small dark spots on the skin, and the tree doesn’t appear to be as lush as it used to be. I did apply dormant oil in the winter.
A: From the pictures you sent, the apple trees look like they have apple scab disease. I have never seen this disease in the Las Vegas Valley, but I have seen it in the Midwest. It could be because of our wet spring weather. Anyway, this disease would be very unusual here, but I think correctable with a little TLC.
This disease can be devastating in climates with higher humidity such as the Midwest. This disease attacks the leaves and fruit and can sometimes cause a total drop of leaves by the tree. Apple scab is a plant disease that requires spraying susceptible trees with a fungicide each year.
We are lucky here because the low humidity of the desert leads to fewer disease problems such as apple scab.
The winter application of horticultural oil probably saved the tree from a lot of problems this year including aphids, scale insects and other soft-bodied insects. Like any pest control insurance, it’s hard to know exactly how many problems you corrected with that winter application, but I’m sure it helped.
Getting back to this problem, just like anything else, the healthier the plant or tree, the fewer disease problems it gets. Concentrate most of your efforts this spring and fall in getting a decent fertilizer applied and covering the soil around the tree with something that decomposes and adds nutrient value to the soil. That will help the tree resist disease problems.
If you didn’t apply fertilizer to this tree in early February, apply one now and repeat the application after you harvest the fruit from the trees. Throw two or three handfuls of 16-16-16 mineral fertilizer on top of the soil where the irrigation water wets it. Keep it at least 12 inches from the trunk when you apply it.
Next, cover the soil under the canopy of the tree with about 1 inch of good compost and water it in. Finally, cover this same area with 4 to 6 inches of woodchips so they decompose and add plant nutrients back to the soil.
After harvesting the fruit, or alternatively in mid-fall around the middle of September, rake the wood chips so that bare soil is exposed and reapply the same fertilizer a second time. Rake the wood chips back on top of the fertilizer and irrigate normally.
Your biggest job this summer is to make sure these trees receive enough irrigation water and at the proper times. Applied irrigation water should wet all the soil under the canopy of the tree. Enough water should be applied so that it wets the soil to at least 18 inches deep. Twenty-four inches deep is even better.
Do not water every day during the heat of the summer or at any time. The wood chips help. Always make sure that you have at least one dry day (no irrigation) during the heat of the summer.
If you are keeping tabs of how much water you are applying, the depth of the water applied to the tree for the entire year should be about 5 feet deep under the canopy. About two-thirds of that amount is applied during June, July and August.
Q: I thought you might be able to help me with this unusual dilemma. I have three rosemary plants in my yard, all in full sun. I have been here for 8½ years. One seems to have changed to small clumps of leaves instead of long branches, one is a mix of both, and one seems to grow normally. They all seem healthy otherwise. Any idea what is going on with these guys?
A: Rosemary doesn’t have a whole lot going on with it that could lead to problems like that. The major problems are root rot from watering too often or lousy drainage and spittle bug. I think a lot of the pest problems are nonexistent because rosemary oil is a natural pesticide. And of course, there’s a lot of rosemary oil in rosemary.
I looked at the possibility of a virus disease, but I could find no mention of it anywhere. I have never heard of a virus disease on rosemary, but from your pictures and description, it could be a vague possibility.
Sometimes weed killers applied close to plants can cause unusual growth patterns that resemble virus diseases. They will grow out of it next year if it’s a weed killer issue.
Another possibility is a mixed planting of upright rosemary and prostrate rosemary. But I think you would’ve seen this earlier than eight years.
What I’m left with is the management of these plants. Specifically, how they were pruned. Pruning these plants deeply or aggressively could cause a response that you described. If you pruned last year, don’t prune this year and see if there is a difference in growth.
Regardless, check to make sure that you don’t have any plugged emitters and they are all getting the same amount of water. Fertilizer applications and sufficient water should solve the problem if that’s the case.
Q: I have two fig trees, 9 to 10 feet tall. Our landscaper pruned at least 3 feet off the top of each one in February. Our black fig tree just started to show some life with new leaf growth, but our white fig tree has no sign of life. Is this telling me the tree is not surviving or just taking longer to produce regrowth?
A: Pruning had nothing to do with their slow spring growth. Figs grow later in the spring than other fruit trees. These are two different varieties of figs with some natural differences between them. One difference is how soon their growth begins in the spring.
Different varieties of fig trees start their growth in the spring at slightly different times. This spring has been unusually cold as well, so give them a chance to grow as this weather starts to warm.
It sounds like the landscaper might have cut the tops back just to lower their height. It’s better to prune them with individual limb removal rather than just lowering their height.
Bob Morris is a horticulture expert and professor emeritus of the University of Nevada, Las Vegas. Visit his blog at xtremehorticulture.blogspot.com. Send questions to Extremehort@aol.com.