Q. I planted two Mandarin oranges from different
nurseries this past spring. One did very
well in full sun from the git-go. The other had leaves that were turning
yellow. I applied iron and nitrogen fertilizers,
but it didn’t do much after a week. So, I constructed some shade over at and it
started looking green again.
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| Sometimes plants need to “acclimate” to their new desert climate. |
A. It sounds like you’ve got your answer; intense desert
sunlight caused leaf yellowing. But it begs the question, “why only one of the
trees if they were both mandarin orange?” You said the trees came from
different nurseries. That might be part of the answer.
sunlight caused leaf yellowing. But it begs the question, “why only one of the
trees if they were both mandarin orange?” You said the trees came from
different nurseries. That might be part of the answer.
But
first, eliminate other potential problems before I get to the nursery
explanation. Make sure your trees share the same microclimate, the soil in both
locations was similar with similar drainage, the soil mix used to plant both
trees was the same, that the roots were kept moist and planted no more than
half inch below the soil surface, that they were staked and watered thoroughly
after planting.
first, eliminate other potential problems before I get to the nursery
explanation. Make sure your trees share the same microclimate, the soil in both
locations was similar with similar drainage, the soil mix used to plant both
trees was the same, that the roots were kept moist and planted no more than
half inch below the soil surface, that they were staked and watered thoroughly
after planting.
 |
| Sometimes yellowing on citrus can be for other reasons. |
You may
be observing differences in how and where your trees were grown versus our
harsh, desert climate. A local nursery used to bring in citrus trees for sale in
containers and put them in an area that had partial shade. They could put them
in full sun and sell them from there, but they didn’t. Too risky.
be observing differences in how and where your trees were grown versus our
harsh, desert climate. A local nursery used to bring in citrus trees for sale in
containers and put them in an area that had partial shade. They could put them
in full sun and sell them from there, but they didn’t. Too risky.
 |
| Sometimes yellowing can be from high light intensity. |
Plants
grown in a greenhouse, under partial shade or in a cool, coastal climate
produce leaves that are different from leaves grown during our harsh desert sunlight
and low humidity. When tender plants are plunged directly into our strong
sunlight and low humidity, the leaves may scorch, yellow or drop from the
plant. The plant is not dead but quickly produces a new set of leaves very
different from its old ones. The newer leaves are smaller, thicker, tougher and
better capable of handling desert sunlight and humidity. The plant has become
“acclimated”.
grown in a greenhouse, under partial shade or in a cool, coastal climate
produce leaves that are different from leaves grown during our harsh desert sunlight
and low humidity. When tender plants are plunged directly into our strong
sunlight and low humidity, the leaves may scorch, yellow or drop from the
plant. The plant is not dead but quickly produces a new set of leaves very
different from its old ones. The newer leaves are smaller, thicker, tougher and
better capable of handling desert sunlight and humidity. The plant has become
“acclimated”.
 |
| Yellowing from an iron problem happens on new growth and lowers the health of the plant making it more susceptible to heat problems. |
Observe
where nurseries are selling plants. Plants sold from shady areas may struggle
when planted in full sun. Plants grown in a greenhouse need two or three weeks
of “acclamation” before they are plunged into an intense desert landscape. This
is true of vegetable transplants as well.
where nurseries are selling plants. Plants sold from shady areas may struggle
when planted in full sun. Plants grown in a greenhouse need two or three weeks
of “acclamation” before they are plunged into an intense desert landscape. This
is true of vegetable transplants as well.
If you
suspect you have a plant which may be acclimating to its new environment,
sometimes it’s easier to strip off the leaves or prune the plant so its new
growth is better acclimated to its new desert environment. In your case, wait
until fall and remove the shade. Let the mandarin orange “acclimate” to its new
home during the cooler fall weather.
suspect you have a plant which may be acclimating to its new environment,
sometimes it’s easier to strip off the leaves or prune the plant so its new
growth is better acclimated to its new desert environment. In your case, wait
until fall and remove the shade. Let the mandarin orange “acclimate” to its new
home during the cooler fall weather.