Larger grapes, in a pinch: Fewer berries mean larger berries

Have you pinched your grapes lately? The berries of table grapes will get much larger if you remove the bottom third of the bunch. You can do this by using your fingers in one pinch. If you don’t like pinching, cut it off with a scissors or pruning shears.

A bunch of grapes has the natural shape of a triangle. Removing the bottom part of that triangle results in a bunch that is relatively round instead of triangular. This results in fewer berries with the resulting berries getting larger.

If you remove other smaller bunches close to the pinched bunch, the berries will get even larger. Berries have size limitations, though, so you can’t get grapes as large as watermelons.

Remove the smaller bunches entirely. When you’re finished, you’ll want the largest bunches of table grapes spaced about 12 to 18 inches apart along the vine.

Q: I have an Independence nectarine tree I have been nurturing for two years. This is the first year I have had fruit. I am seeing something on the fruit that looks like dried droplets of sap. Do I have some sort of blight on the fruit? Will I just need to take this plant out?

A: This type of sap, with all the scarring you see on the fruit, is caused by small puncture wounds to the fruit’s skin. When the skin is punctured on immature fruit, sap oozes out of the hole and dries. Sometimes this dried sap looks like little squigglies coming from the skin.

Insects called thrips cause these holes in the skin. These insects feed on the sap by pushing their long skinny mouth part, called a stylet, through the skin and rupturing it.

In wetter climates, these puncture wounds can cause the fruit to rot because of infections. Here in our hot, dry climate, the rotting doesn’t occur as often.

To keep your nectarine fruit tree from blemishes and scarring, apply protective sprays to the fruit early in the season. The most effective organic spray contains Spinosad. You don’t want to spray Spinosad or any chemical over and over again or you can end up with some problems.

You want to use two or three different sprays in rotation with Spinosad. Other organic sprays you could use in rotation with Spinosad include Neem oil, pyrethrum and insecticidal soap.

Remember that organic sprays do not last very long and may not cure a really bad problem that is already underway. These chemicals are more effective when they are used to protect fruits when you see small numbers of pests.

Q: What type of mulch is not recommended to put in flower beds? I thought I remembered it being redwood mulch but I can’t find anything on that. Could it have been cedar? My landscape guy says the shredded cedar is not a problem for vegetation.

A: Either one will work fine. Redwood and cedar mulches don’t decompose as quickly as pine and are usually prettier.

Both cedar and redwood have phenols that help the wood resist decay by fungi and bacteria. There doesn’t seem to be a problem for bedding plants.

My preference is a variety of mixed woods but we do break down fairly quickly (two to three years) and must be replaced.

Many homeowners like the look of redwood and cedar mulches. They don’t break down as fast and therefore last longer in the landscape. They may be more expensive initially but they don’t need to be replaced as often as pine mulches.

Q: I have a chaste tree that has been growing in my backyard for about seven years. The branches have always been full of leaves and I would get an abundance of beautiful purple blooms.

Last spring, I noticed there were not as many leaves and I would get purple flowers only here and there. This spring again the leaves are sparse and the branches are mostly bare. Should I be doing something extra to bring back the tree’s lushness?

A: Vitex, or chaste tree, is relatively pest-free. It originates from the Mediterranean region, where the summers are usually hot and dry and the winters cool to cold and wet.

The only real problems the plant has are if the roots remain too wet or the plant doesn’t get enough water. So my reaction to your question was concern about your irrigation practices; either watering it too often or not giving it enough water when you do irrigate.

Both could cause similar problems. If the roots stay too wet, root rots develop and you might see a thinning canopy and branches dying back. Watering too often results in poor growth or worse. If overwatering continues, you would probably see die-back in the tree and eventual death from root rots.

If the plant does not receive enough water, the plant canopy will begin to thin out and along with that a reduction in blooms. If you feel like this tree does not get much water, then try flooding the area around the tree once a week in conjunction with your irrigations. If the problem is not enough water, you should see a reaction to additional applied water in three to four weeks.

It also will do best with irrigations similar to those of your landscape or fruit trees. This means regular deep irrigations.

Avoid daily irrigations. Water about twice a week during the hot summer months. In the spring and fall months, water deeply and thoroughly once in a week. As temperatures cool towards winter, you would probably irrigate deeply every 10 to 14 days.

Q: I’m having a problem with my Japanese blueberries. Some are fine. But the two on the end appear to be drying out, but only toward the top. Do you have any idea what’s causing this? The soil isn’t dry and they all get the same amount of irrigation.

A: Japanese blueberries are sensitive to sun damage. If the main trunk receives intense sunlight for long periods during the summer months, you could develop sunburn or sunscald.

I would guess that something has damaged the trunk or larger limbs toward the top. Inspect the trunk closely just above the point where the tree is still healthy. I suspect you’ll see bark peeling away from the trunk.

Pull any loose bark off of the trunk. Examine the wood under the bark you removed. Look for traces of sawdust in channels that snake along the surface of the wood.

If you see this kind of damage, borers have been at work in the trunk’s sun-damaged area. You can apply liquid soil drenches that are insecticides at the base of ornamental trees to arrest damage from borers. This insecticide is pulled up inside the tree, which then protects the tree when borers attack it.

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