Q. Eleven of my 50 young pomegranates
have leaves yellowing and dropping off. I water this area once a week by
flooding. I sprayed a weed killer, 2,4-D, near the pomegranates but I protected
each one with plastic to avoid damaging the trees. Where did I go wrong here?
If the weed killer is the problem, is there any way to save them?
have leaves yellowing and dropping off. I water this area once a week by
flooding. I sprayed a weed killer, 2,4-D, near the pomegranates but I protected
each one with plastic to avoid damaging the trees. Where did I go wrong here?
If the weed killer is the problem, is there any way to save them?
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| It looks like the pomegranates were planted in a depression. The more I look at these pictures the more I’m concerned that it the roots may be kept too wet. The only way to know for sure is to use the soil moisture meter and measured the soil moisture just before the next irrigation. Generally speaking, pomegranates and most long grasses are not compatible. Another possible option is to plant pomegranates on a raised area of soil rather than a depression. |
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| Even though the soil is cracked on the surface it tells you nothing about how dry it is only a couple of inches below the surface. Many weed killers can travel with water. Make sure no water is added to these plants within 24 hours after we killers are sprayed on the soil. |
A. When I first saw your
pictures I thought the soil was too wet. But I read your email that they were
watered only once a week. Watering once a week in mid spring should pose no
problem if the soil is not a heavy clay. If the soil is a heavy clay and
remains wet a couple of days, this could cause leaf yellowing and dropping.
pictures I thought the soil was too wet. But I read your email that they were
watered only once a week. Watering once a week in mid spring should pose no
problem if the soil is not a heavy clay. If the soil is a heavy clay and
remains wet a couple of days, this could cause leaf yellowing and dropping.
In the picture, I saw grass growing close to the
pomegranates. If watering only once each week, I assume the grass is Bermudagrass.
Tall fescue should need watering more often than this. Grass growing close to
these trees will cause them to grow more slowly. Particularly Bermudagrass. So
it’s always a good idea to remove grass at least 3 feet from a fruit tree.
pomegranates. If watering only once each week, I assume the grass is Bermudagrass.
Tall fescue should need watering more often than this. Grass growing close to
these trees will cause them to grow more slowly. Particularly Bermudagrass. So
it’s always a good idea to remove grass at least 3 feet from a fruit tree.
The leaf yellowing could also come from a lack of
nitrogen in the soil. However, if you are fertilizing that grass there is
probably plenty of this fertilizer escaping to the pomegranates. Removing grass
3 feet from the tree will reduce competition for any fertilizers applied.
nitrogen in the soil. However, if you are fertilizing that grass there is
probably plenty of this fertilizer escaping to the pomegranates. Removing grass
3 feet from the tree will reduce competition for any fertilizers applied.
Now on to the most likely problem; weed killers. It
helped that you covered each of the trees with plastic before spraying. It’s
even more important if you spray this kind of weed killer when temperatures are
cool and there is absolutely no wind. Hot soil surfaces cause dandelion killers
like 2,4-D to volatilize (turn into a vapor) and move very easily with the very
slightest air movement.
helped that you covered each of the trees with plastic before spraying. It’s
even more important if you spray this kind of weed killer when temperatures are
cool and there is absolutely no wind. Hot soil surfaces cause dandelion killers
like 2,4-D to volatilize (turn into a vapor) and move very easily with the very
slightest air movement.
 |
| This is 2,4-D damage, dandelion killer, on tomato. If the tomato plant is growing, the growth will become deformed. |
Damage from 2,4-D is easy to identify when the plant is
growing and producing new leaves; new leaves are deformed. If the plant is not growing
and producing new leaves, leaves turn yellow and drop. The branches that
supported them may or may not die as well. All you can do is wait and see what
happens.
growing and producing new leaves; new leaves are deformed. If the plant is not growing
and producing new leaves, leaves turn yellow and drop. The branches that
supported them may or may not die as well. All you can do is wait and see what
happens.
 |
| This is weedkiller damage on grape. The weedkiller is unknown but the damage is unmistakable. |
I am concerned with the plastic. Make sure that the same
side of the plastic using contact with the plants and that you don’t
accidentally wrap the plant the wrong way.
side of the plastic using contact with the plants and that you don’t
accidentally wrap the plant the wrong way.
I think a better weed killer to use for your purpose might
be Roundup. It does not volatilize as easily as 2,4-D. For it to work, the
spray must land on green leaves or green limbs. If you prune pomegranates so
their lowest foliage is about knee height from the ground, it will be less
likely to be damaged.
be Roundup. It does not volatilize as easily as 2,4-D. For it to work, the
spray must land on green leaves or green limbs. If you prune pomegranates so
their lowest foliage is about knee height from the ground, it will be less
likely to be damaged.
Keeping grass 3 feet
from the trunk will also help. A small plastic bucket with a hole drilled in
the center of the bottom, attached to a spray wand, will help contain the spray
and directed toward the weeds.