HEAT STRESS AND CITRUS TREES

Signs & Symptoms of Heat Stress:

In the heat of the summer, it is important to protect your trees against heat
stress. One of the best ways to do this is through a program of deep watering.
Do not use anything with oil in it on the tree. Use only water base sprays as
oil on the leaf surface is very bad in the heat of summer. Remember when you
spray, that you plan to eat the fruit from this tree. We would only use and
recommend organic pest spray

1. If in the heat of the day you happen to notice new growth “shoots” hanging
limp (wilting) and looking really down and out, do not be too alarmed. That is a
sign of heat stress and your trees is begging for a little cooler environment.
You might want to think of a place that offers a little more shade in the heat
of the day. If your trees are wilting, but the soil is wet, mist the leaves down
around mid-day. (This does not burn the leaves despite the myth.) The extra
humidity will protect the tree from the heat. Trees planted this year, or
heavily pruned over the winter should have their trunks painted with Tree Trunk
Paint.

2. Leaves will turn a pale or light green color with a cloudy white look to then
when they are exposed to intense direct sunlight. This is called “bleaching”; it
is basically a tree “sun burn”. To help prevent this, slowly adapt your tree to
full sun by going from shaded, to partial shade, and then on into full sun.

3. You might notice your leaves edges wanting to curl upwards. Your tree is
letting you know it is being exposed to the maximum amount of sunlight and heat
it can handle. The roots are having a hard time keeping enough stuff flowing to
properly “cool” the leaf surface. Black pots can get very hot in direct
sunlight. In fact they often get to hot. Your root ball temperature is best in
the 70-80’s and should not go over 100 degrees. Too hot of a pot will look like
sign 1 and 3. To help, first make certain you are providing adequate water.
Shade the pot with an ivy or decorative cloth. Airflow is also a great way to
cool your plants. That is one main reason greenhouses have fans.

If your trees are wilting, but the soil is wet, mist the leaves down around
mid-day. (This does not burn the leaves despite the myth.) The extra humidity
will protect the tree from the heat. Trees planted this year, or heavily pruned
over the winter should have their trunks painted with Tree Trunk Paint.

A few old, but very true rules to keep in mind this summer in the citrus garden...

1. Avoid watering during the heat of the day. If you mist or foliage feed, you
must do it in the late evening.

2. Do not use anything with oil in it on the tree. Use only water base sprays as
oil on the leaf surface is very bad in the heat of summer. Remember when you
spray, that you plan to eat the fruit from this tree. We would only use a
recommended organic pest spray.