Color change in fruit might not signal ripeness

I will be giving a class on summer pruning Saturday from 9 to 11 a.m. at the Center for Urban Horticulture, 100 yards east of the orchard at Horse Drive near Decatur Boulevard in North Las Vegas, in the outdoor auditorium. There is no fee for the class. Visit my blog or send me an email for more information.

The fruit in the grocery store looks good. But frequently when you taste it, the taste does not match the look of goodness that you thought was there. This is why.

Ripe fruit is different for the tree than it is to humans. Ripeness to us usually means a color change from green to red, yellow, purple or orange. Fruit that is ripened fully on the tree will start to be slightly “soft” when squeezed.

The bird doesn’t have hands or fingers so they “beak” the fruit. If the fruit does not taste good to a bird, the bird tries a different fruit or fruit from a different tree. Of course that is really irritating because they often don’t just damage one fruit.

A color change can be an indicator to you that harvest time is close. Harvesting a bit early can keep the fruit from dropping because of wind or sampled by hungry birds.

When fruit is very unripe, the seed is not mature enough for good growth, the tree usually will hold on to the fruit unless winds are unbearable. When fruit ripens, the tree holds on to the fruit stronger. And the answer is no, you cannot “glue” fruit back on to a tree when it is blown off due to winds like we had Sunday morning.

Birds use color to indicate ripeness as well, along with a sense of smell and, of course, the beak test. If you want to stay ahead of birds and fruit drop due to wind, harvest fruit that can develop off of the tree (apricots, peaches, plums not cherries, grapes or figs) when you see a color change in the fruit but they are still firm.

Let them ripen further off of the tree on the kitchen table. Even green fruit, such as green apples and green plums, have a slight color change from green to light green indicating a change in maturity.

Q: Our neighbor’s pine trees are going to be cut down soon. I would like to use the wood chips from the tree as mulch for our recently planted fruit trees. I remember you recommend 4 inches deep. What are your thoughts on fresh mulch as this?

A: Nothing wrong with fresh pine chippings. We provide an assortment of wood chips, fresh, at the orchard for the public. You will have no problems with it. As it is decomposing, make sure you give the soil some extra nitrogen among the bark and soil.

Keep any wood mulch away from the trunks of new plants, about a foot for the first few years until the bark on the trunk gets woody. If they grind out the stump of the tree with a stump grinder, those are some of the best wood chips.

Q: I have several fruit trees (apricot and plum) that have meadow grass in their wells and around them. The grass is a wide bladed variety that had an extensive root system including rhizomes. Can I safely spray Roundup on the grass without harming the trees? This assumes that I cover the trunk and canopy from overspray. Does the Roundup end up in the ground only to harm the trees roots?

A: No problem spraying the grass. Yes, it is best if you put some cardboard or something to keep the overspray off the trunk. If the trunk is woody and not green, it should pose no problem but it is better to be safe than sorry.

I would cut the grass back, spray it with water to get the dirt off of it, make sure it is watered and happy, then kill it with Roundup. Apply just enough to wet the grass and no more.

You do not need to, nor should you, overwet the grass. Apply enough to wet the leaves. You can go back a few hours later and respray it if you are not comfortable with just wetting the leaves.

Roundup has been known to work better if you put in one-half teaspoon of dishwater detergent in the spray mix before you spray. Adding a small amount of soluble nitrogen fertilizer to the mix, such as ammonium sulfate, also is known to help it work better.

The detergent or wetting agent helps the Roundup penetrate the grass blades. Twelve hours later 95 percent of the Roundup will be absorbed, and it no longer makes any difference if the grass gets wet from a sprinkler or not.

You should start to see dieback in about seven to 10 days unless something has been added to the Roundup for a quicker kill.

Q: For the past couple of years my oleanders have suffered severe frost damage and have been slow to recover in the spring. They are all mature plants. While I was trimming the dead leaves recently, I noticed that the oleanders with red flowers had less damage and were recovering more quickly than the others that have pink flowers. Is this unique to my yard, or have you heard of this from other gardeners? I’m considering removing the ones with pink flowers because they look ratty for so long and are not earning their keep.

A: The different colors of oleander represent different varieties. And yes, they have different tolerances to cold.

If you are not having luck with one variety, take it out and replace it. The most cold tolerant seem to be the red ones and white ones.

I am not saying not to plant other colors or varieties, but if you want a sure thing with no cold damage stay with white or red types.

Q: My lemon tree is about 5 years old, and it has a lot of flowers and tiny lemons. The tree looks healthy, but I have noticed the leaves are turning yellow. I water it every day about 10 minutes, six days a week. We have artificial grass about a foot away around the trunk. Am I overwatering it or is the artificial turf the culprit?

A: I don’t think the artificial grass has anything to do with it. I suspect that maybe the soil is being kept too moist. The artificial turfgrass might be acting like mulch and keeping the soil wet longer than if it were not covered in anything.

Water deep and infrequently. It should do okay watered twice a week now with about 20 gallons or so each time.

Try getting some iron chelate spray and spray the foliage in the cool morning hours. Add some spreader to the spray to get it to go into the leaves or use some liquid detergent but be careful with store-bought liquid detergents. It is possible they can cause some leaf damage if you aren’t careful with them.

You have to spray liquid iron about four times: once every couple of days for four sprays total. Spray until the iron solution drips from the leaves. Make a new batch each time you spray and use the spray fresh each time because of our alkaline water.

Q: Someone gave us a Mason bee house to use. I saw in a July 2011 post on your blog that there really aren’t mason bees in the Las Vegas area, but there are leafcutter bees. Do you think the leafcutters would use the Mason bee house? I know leafcutters stuff the hole with leaves so the fact that the Mason bee holes are larger might not be an issue.

A: I think the holes will be fine. The leaf cutter bees will take holes up to three-eights of an inch easily and I think mason bee holes are about five-sixteenths of an inch, which should be fine for both bees.

Most people don’t know the difference but be delighted that local bees are using it. Have fun with it!

Bob Morris is a horticulture expert living in Las Vegas and professor emeritus for the University of Nevada. Visit his blog at Send questions to