Q. My Asian pears look
sickly again this year with yellow leaves. Last year after their planted the
new growth was yellow and again it’s happening this year.
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| New growth on Asian pear is light colored or yellow. This can be for many reasons. |
A. There are several
possibilities why plants have yellow leaves when they’re young. Some plants have light colored leaves when they are young and get darker as they get older. If this is the case, don't worry about it.
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| Chojiro Asian pear growing in the Las Vegas Valley in the Eastern Mojave Desert. |
Planted too deep
The first is
rather simple. Their planted too deep. Fruit trees must be planted the same
depth they were when growing in the nursery. Those fruit trees that are grafted
or budded must have the dogleg above ground.
If the hole is dug too deeply and the soil is amended, it’s
possible the tree will sink deeper after it’s planted and soil will fall around
its trunk. Wet soil around the trunk can rot it. This is the reason it is best
not to dig the hole deeper than is needed for the roots unless there is a
drainage problem.
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| This pomegranate was planted in a depression in a lawn. Are the roots staying too wet? No way to know until you check the soil and see how wet it is just before the next irrigation. |
Soil doesnt drain water
The first sign there is wet soil around the trunk and it’s
starting to rot are yellow leaves. If not corrected, it can kill the tree. If
the bud union is below the soil, water can rot the union and it will die. In milder
climates the top part of the tree can grow roots and you will lose the benefit of
the rootstock.
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| This is an apple tree growing in an orchard in the mountains of Lebanon on terraces. The soil was kept too wet near the trunk the tree developed collar rot. |
Borers
Another reason for yellow leaves are borers. You would
think that trees coming from a nursery wouldn’t have insect problems but they
do. After supervising the planting of hundreds of fruit trees, I would estimate
there are borers in two out of every 100. Trees most susceptible include peach,
nectarine and apple. Others are also susceptible but less so in my experience.
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| Borers in ornamental plum |
Water drainage through the soil can also be a problem. If
watering too often and the roots stay wet, they will begin to rot. Rotting
roots decrease the plants health and this shows up as yellow leaves in the top.
Check the soil moisture and make sure the soil is not watered daily.
Soil improvement
Sometimes the soil is not improved enough at the time of
planting. I like to see about 50% of the volume of the soil used for planting
amended with compost if this is desert soil. Less compost is needed in other
soils but it’s still a good idea.
Compost improves water drainage through the soil but it
also helps the soil hold water. I know it sounds crazy but the soil structure where
air is contained is improved while also the channels for draining water are
improved at the same time. It is either drainage/water problem, planted too
deep, borers or lack of fertilizer.
If this lack of color continues, spray the leaves with a liquid fertilizer spray.
Mixing a liquid fertilizer
and spraying the leaves.
Use either a Fertilome,
Grow More or even Miracle Grow product with high nitrogen. A lawn-type fertilizer
would be good for young trees.
You will need:
- Distilled water (tap water in Las Vegas is pretty bad quality)
- Water soluble fertilizer
- Use liquid spreader (baby soap
or Castile soap liquid or EZ wet from
Viragrow) to help fertilizer get inside the leaves and. Add what it recommends
on the label or ½ tbs per gallon.
Steps
- Add water to the sprayer
so it is half full
- Add water soluble fertilizer at
rate on label.
- Finish adding water to the
spray so that it mixes all well.
- Add spreader (EZ Wet) to
the mix and stir.
- Spray leaves to runoff,
top and bottom.
- You should see a change in leaf color in 48 hrs
