Citrus Tree Maintenance

Karen Cambre, Sharpe, Kenneth W.

News article: February 18, 2019

scale on citrusjpg

Winter is escaping us quickly. Still much to do to get ready for spring and not really sure how much time is left to do it.

Citrus trees are typically considered to be medium to low maintenance trees, but now is time to provide some of that care.

Check your citrus trees for scales now. I have seen a number of trees that have the insect scale on the underside of the leaves. Scales appear as gray or white bumps on the underside of the leaves. I have also seen some brightly colored orange to red scales on citrus. These insects are sucking plant juices and robbing plants of much needed nutrients.

Now you can use dormant oil to suffocate and control scale, but you have to do this before the temperatures climb. Oil can burn foliage in the heat, so check the label for maximum temperatures and consult weather reports before spraying.

Citrus will also need to be fertilized from late February to early March.If you are just planting a new citrus tree this year, use about ½ of a pound of 8-8-8 once the tree starts to put out new foliage in March. For trees that have been planted for a year or more apply fertilizer at the rate 1½ pounds of 8-8-8 or 1 pound of 13-13-13 per year of age of the tree up to a maximum of 12 years.

Spread fertilizer around under the canopy of the tree and go out as far as the limbs reach and then water the fertilizer in.

Citrus trees that have been planted for 4 years or longer should receive a second fertilization at the start of June. The summer fertilization rate will be ½ pound of calcium nitrate per year of tree age up to 12 years of age. The June side dress will help to eliminate alternate bearing trees that produce fruit one year and then skip a year.

If you have excessive lichen growth, take advantage of the cool weather to gain control. Lichen is the mossy, greenish gray growth that grows on the trunk and twigs of trees and some shrubs. Lichen is not harmful to plants unless it grows in such a way to block sunlight to plants, but some people find it objectionable.For control use a copper fungicide and make a dormant season application. There are lots of coppers to choose from that are mixed in water to make a spray, such as Kocide and tri-basic copper sulfate.

Lichen that is sprayed with copper will not readily fall off, but you will know you have control if it turns a copper color. It will take several months before lichen actually falls off.

I have been hearing from a lot of citrus owners who are seeing curling leaves. They also report that the leaves have squiggly white or gray lines in them. The culprit is the citrus leaf miner. You cannot control the miner when he is between the leaf tissue layers. Wait for the new spring flush of leaves and spray the new growth with Spinosad. This should help control the spread to the new leaves and then do this again for the other leaf flushes later in the year usually mid-summer and again in the fall.

I would prefer to do any citrus pruning in the dormant season, January and early February. While I would not do any radical pruning now, you can still remove those vigorous long growing shoots that stick up at the top of the tree. This will help control the size of the tree and keep your harvest in a safer height zone to pick.

Trace the long shoots back to their origin on the larger branches and cut off flush at the point of attachment. This will eliminate that branch and it will not grow back. If you just cut the long shoot off flush with the canopy, it will regrow and 4 or 5 new shoots will replace the one.

2/14/2019 5:02:51 PM
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