Q: I planted a Bosc pear tree seven years ago not realizing it required a second pollenizer pear tree. For several years, I did get a few pears even though the tree had lots of flowers. I think my neighbor’s pear tree was the pollenizer, but it seems to be failing. I have no room to plant a pollenizer pear tree. Not sure what to do.
A: I have grown Bosc, Anjou and Bartlett here in the Mojave Desert in the past and noticed the fruit set wasn’t great in the Bosc and Anjou compared to the Bartlett. It is possible it might be a humidity problem similar to our problems with sweet cherry and Hachiya persimmon growing and setting fruit in our climate.
Compared to Bosc and Anjou, Bartlett and red Bartlett seem to set fruit better in the desert when there is plenty of flowers and honeybee activity. Keep that in the back of your mind.
Since Bosc needs a pollenizer tree, you will have problems producing fruit if there is no other European pear flowering at that time. It might be possible to buy a Bartlett and plant it on the south side of that tree, 18 inches away, and prune out some limbs to make room for it. In other words, integrate another pear that flowers at the same time and see if that helps with the fruit set of your Bosc pear. Bartlett is a good pollenizer for Bosc.
Make sure you have rosemary or other winter blooming herbs to attract honeybees to the backyard that time of year. Anything that blooms during the spring months and attracts bees will work. Because pear blooms a little bit later than some other fruit trees, you might also consider attracting leaf-cutter bees as pollinators to your yard.
Try putting a small birdbath or shallow water source and that will attract honeybees as well. When it’s warm, honeybees haul water back to their colony. Put rocks in the birdbath so that honeybees have a place to land and retrieve water.
If you can synchronize the blooming of these two pear trees, and you still don’t get fruit set on the Bosc pear, you can assume it’s a humidity issue. If it still doesn’t set fruit, get rid of the Bosc and at least you can have a Bartlett. I would look closely at red Bartlett if you want the red color, but both Bartlett varieties work here.
Q: How often do deciduous fruit trees, in this case, a Blenheim apricot, need to be watered during the dormant season?
A: It’s hard to give a blanket recommendation about how often to water because of the differences in soil, root growth and if people are using a surface mulch or not. Because of these differences, routine irrigation might vary a couple of days either way.
The best way is to use a moisture sensor such as those inexpensive houseplant moisture sensors. Insert the tip in the soil about 6 inches deep and irrigate when the meter is around six. You should be at able to water no sooner than every seven days and maybe every 10 days depending upon your conditions.
But if the tree is surrounded by dry soil it may be closer to seven days. If the tree is surrounded by other trees that are irrigated, it might be 10 days. And if you have the soil covered in 3 or 4 inches of wood chips, you can extend it perhaps an extra two days. That’s my best guess.
But you are better off using a moisture sensor to get it more accurate than this. To determine the number of minutes to irrigate, I use a long probe like ⅜-inch rebar and push it into the soil after irrigation. It’s hard to push it deeper if the soil is dry beneath where you water. Recently at one of my classes, someone mentioned they are using a wooden dowel to do the same thing.
I just push it down until it’s hard to push any further and that tells me how deeply I’ve irrigated. With fruit trees, I like to irrigate 12 to 18 inches deep.
Q: We have a vegetable garden and an ornamental garden. We didn’t think about it, but we just installed a water softener. This softened water also comes out of the garden hoses. Is this water bad for our plants?
A: Yes, it will be a problem if you water with sodium-based salts from the water softener in it. Sodium is toxic to plants. This inexpensive salt used in water softeners also contains chlorine, which is also toxic to plants. A double whammy.
You have three options. The first is to run a new water line and hose bib from a point upstream of the water softener and use this water for irrigating. Secondly, install a hose bib from the irrigation line used for the garden since the water supply for outside irrigation is connected before the water softener.
The third option is to use potassium-based water softening salts rather than sodium-based salts. These water softener salts are more expensive but less damaging and will still soften the water. You’ll find this type of salt for water softeners anywhere that sells water softener salt.
Q: I love my lemon bottle brush shrubs, but the leaves started yellowing. l recently added 5 inches of organic topsoil. Additionally, l think l should add acid. What kind of supplement should l use for a long-term solution?
A: Leaf yellowing can be caused by many different things. With bottlebrush, it is frequently a shortage of available iron to new growth. More importantly, the soil is collapsing resulting in poor drainage and not enough air reaching the roots.
I see this often when any bottlebrush is surrounded by rock mulch. Over time, the soil around the roots becomes mineralized. In my opinion, all bottlebrush plants, in general, should not be surrounded with rock covering the soil.
Once leaf yellowing due to a shortage of available iron, it cannot be reversed quickly by adding soil amendments. The most immediate color leaf reversal would be spraying the leaves multiple times, a few days apart, with an iron solution. But the yellowing will return to new growth as the iron runs out.
Adding an iron fertilizer to the soil, such as an iron chelate, lasts longer, up to about one year. It is added in early spring, about now. But the next year you need to add more iron chelate to the soil before new growth begins.
But when iron is added to the soil, the leaves that are yellow remain yellow. Green leaf color only occurs in new growth that hides the yellow leaves until they drop off. To turn yellow leaves green again requires spraying the plant with the iron solution I mentioned earlier.
For the long-term, you must improve the soil where the plant is growing so that the alkalinity of the soil is reduced and the roots have better access to air. This can be done by adding compost to a soil that has become mineralized and covering the soil with wood chips rather than rock.
When preparing a spray solution that contains iron, follow the label directions. But I suggest using either distilled or reverse osmosis water rather than tap water. This is because of the alkalinity in our tap water. In distilled or reverse osmosis water, this alkalinity is removed. I am concerned that the alkalinity in tap water might interfere with the effectiveness of your iron sprays.
I would also include something to make the spray solution wetter. In a pinch, you can use a liquid dishwashing detergent but it’s not ideal since it contains so many additives such as hand lotions and perfumes. It’s better to use a liquid detergent that is purer such as Dr. Bonners or a detergent made from Castile soap.
Both the purified water and liquid detergent is important because it helps move the iron contained in the solution through the leaf surface and inside the leaf.
Spray the leaves long enough so that the spray solution begins running off its surface. Spray both the upper and lower surfaces of leaves so that the sprayer is taken inside the plant more effectively.
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.