This column is meant to help explain why we sometimes have failures in our desert gardens and what we can do to increase our successes. Desert gardening is not an easy way to garden.
My blog, Xtremehorticulture of the Desert on blogspot, has these questions and more along with pictures to help tell the story. This month on my blog I will be talking about desert lawns and how to manage them.
Q: Can you recommend a pesticide to protect backyard-grown fruit trees from ants? They are crawling up the trunks and they get to the fruit before the birds even have a chance, let alone us!
A: The ants usually first go up the tree and into the leaves for honeydew from aphids. They seldom attack fruit that is firm, but usually attack fruit that is already soft.
Because they are after honeydew (the excrement from aphids that is really leaf sap full of sugars ), the ripe fruits are a natural place for them to look for additional food.
There are a couple of things you can do. First is to find and treat the ant nests . Follow these critters back to where they are coming from and pick up some Amdro . Treat the ant nest in the ground. It is not a problem to use around fruit trees.
Secondly, spray the fruit tree with insecticidal soap to reduce the aphid population. You will have to do this multiple times, perhaps once a week since soap does not have any staying power and only kills insects it comes in direct contact with.
Thirdly, harvest the fruits early when they are still firm and not soft. Remove bird-pecked or damaged fruit. Let firm fruit ripen (soften) at room temperature in the house and they will still be very high in sugars and taste great. This is usually about a week before they are fully ripe on the tree.
If you do not know when this is, then mark it on your calendar this year so next year you will know the approximate harvest time. Or you can simply taste a firm fruit after it has turned color. When it is sweet but still firm, pick the ones that are ready and continue picking over the next couple of weeks .
Q: My Kieffer pear, which set no fruit at all this year, got extremely chlorotic from early April to now. I treated it with Western Organics’ Super Iron Chelate, per package instructions. I see noticeable improvement, but does it need a second application? If yes, at what interval? Does this condition have any relation to the lack of pears this year? Normally, this tree yields more than a hundred pounds of fruit per season.
A: As far as the yellowing goes, if it is lack of iron, the veins of the yellow leaves should be dark green while the spaces between the veins may be light green or even yellow in severe cases. In very severe cases the leaves will yellow and not have any green veins at all. In extremely severe cases the leaves may turn black and scorch.
I do not know the product you used and the quality of the iron chelate. If this chelate is not EDDHA, then you run the risk that the iron may not be very effective. Other chelates drop their iron if the soil pH is too high and then the iron does not make it inside the plant.
I would strongly suggest you make sure the chelate is EDDHA. If not, and the label permits, you can mix it with water and use it to spray the foliage . If fruit is present, you do run the risk of discoloring the fruit with the iron.
You can try adding this chelate with a diluted source of vinegar to try and push the pH lower while making the iron available. This is a hit and miss approach. You are running out of time so I would put this on the soil as soon as possible .
If the tree did not set fruit this year, did you see flowers? If you saw flowers but no fruit, then it was a failure in pollination or a late freeze that took out developing fruit when they were very young. If you saw no flowers, then we must make sure that fruiting spurs, or short shoots, are present on the tree.
Make sure short shoots or fruiting spurs were not accidentally pruned off the tree. You can see a picture of a pear’s short, fruiting shoot on my blog.
Pears also can get into an alternate bearing cycle. This means that they can set fruit heavy one year and very little the next. If your tree bore heavy last year, then alternate bearing is a possibility. Next year, if you’re pear bears heavy again, then thin it hard. Remove fruit from the tree when it is very small so that only one fruit remains per cluster of fruit.
Forty or 50 leaves are needed to support one fruit. By removing fruit in a heavy-set year we can sometimes help shift it back to producing every year.
Bob Morris is a horticulture expert living in Las Vegas; he is on special assignment in the Balkh Province, Afghanistan, for the University of California, Davis. Visit his blog at xtremehorticulture.blogspot.com.