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Orange tree leaves, branches dying!


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#1 Guest_B.J._*

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Posted 05 February 2008 - 01:04 PM

I have a four foot tall orange tree that did very well outside this past summer. It ripened fruit , we picked it -- it was good.

Now I have it inside and it's losing leaves. Even branches are dying. The leaves yellow, dry up and fall. The dead branches look like they dried right out. I sprayed it with a pesticide about two weeks ago but it doesn't seem to have helped.
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#2 Janet Macunovich

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Posted 05 February 2008 - 04:23 PM

Look at your orange's leaves for shiny, sticky spots and scruffy, tiny white flakes like dandruff. If you haven't learned to see scale (source of the sticky stuff) and mites (they create the dander) you may want to look at the leaves under a magnifier. Because you don't mention stickiness I'll guess it's mites that are at work. If so, you're going to need to wash that plant repeatedly, every few days for at least two weeks, using oil soap and water or insecticidal soap or pepper soap, to get ahead of it.

Mites and scale both hurt a plant by sucking its sap. That dries it out in spots and weakens it overall. Your tree was probably battling mites or scale for some time. I say this because of the dead twigs. These pests usually do their greatest damage to twigs that are still soft, newly formed. That damaged wood dies later when the tree runs into enough trouble and looks to cut its losses by shedding what it can. A tree that suffered mites or scale during its new growth phase might not lose that wood until it ran into the trouble of low energy -- low light.

Nutrition can figure into any leaf loss problem, too. It can be a primary cause but also might act as an insect-accelerator or disease-inviter. So most of the time when there are insect or disease problems you'll hear me and others say, in effect, "Clean up the currrent problem and then make that plant healthier." Leaves that formed without adequate nutrient may not hang on as they should. If they're thin and deficient, they're not able to stand up to their pests. Pests proliferate that might otherwise be held to a dull roar by the pest-population-control chemicals a healthy plant can produce. In the case of citrus, healthy leaves are THICK and dark, dark green. If they're not, they needed more raw material to work with while they were developing. In that case I'd look to increase light, water and/or fertilize the next time the plant is in active growth -- this coming spring and early summer.

More on the mites. The scruffy white dander (tiny, tiny flecks that are white-sandy or almost crystalline) all over the leaves is accumulated empty shells from mite eggs. With a magnifier you might find only one or a couple of adult mites but where there is a lot of dander there were a lot of eggs. Either you are missing seeing the adults or perhaps their numbers were reduced by your pesticide application. But although pesticide or washing might kill some active mites it won't get them all and won't affect those in the egg. Which is why repeated attacks are necessary to control mites. The hotter and drier the place where the tree is (like inside a house in winter) the faster mites reproduce.

Perhaps your tree has citrus mite (citrus red mite) but it's more likely it's hosting common spider mite (common red mite). Whichever it is, if you have other citrus plants in the vicinity they're at risk. If it's common mite it can also live on most other interior plants. Since it's easy to carry such tiny things as mites or their eggs from place to place, try to wash your hands between touching the orange tree and any other plants until you get the mites under control.

The "red" part of either mite's name is misleading. Only at one point in their life cycle and in certain conditions do they show any red. Most of the time they'll look white or glassy-clear.

If there are sticky places on your orange you may have another problem also common to citrus. That's scale insects. Look for tiny crawlers (immature scales) or adult scales (flat, non-moving, fastened-down, brown). Shiny honeydew (scale excrement) is a pretty sure sign they've been there, sucking on and drying out the leaves and twigs. Scales may be temporarily out of a picture after a pesticide application, but consider them down for the count; not out. Like mites they can rebuild their population fairly rapidly from those that were protected within egg cases and other survivors. So repeated washing or pesticide applications are necessary.

Whatever you do -- more pesticide or alternative pesticides like the soaps or hot pepper -- keep in mind that it's not the strength of the stuff that counts. It's the repetition. Follow-up to kill the next batch as it hatches, and the next after that. Depending on their "date of birth" and also air temperature, humidity -- which can vary between places on a plant -- mite eggs that application Number One doesn't kill will hatch in 1 to 7 days. That next generation and any survivors (there are always survivors) can be laying new eggs in 5 to 7 days. Thus the two week war-of-many-battles.

Good luck! Even having lost so many leaves and limbs the plant can recover, albeit starting over smaller. What it needs is the best light energy you can get it. (Can you shine a grow lamp on it? Or move it to a cool, sunny room if it's quite warm now?). And it needs your help to keep new mites from sucking dry its winter-deprived foliage.

I hope you don't feel bad that this plant lost so much ground. Mites are common on interior plants. And hard to see "for sure." You can see the dander by eye, but won't recognize it if you haven't seen it before. It usually takes a magnifier to see the mites themselves. To see them well enough to count their legs so you're certain they're mites (8 legs) and not insects (6 legs) may take a 30-power magnifier, depending on your eyes. Look at the photos at these links to get an idea what you're looking for --

http://www.ctahr.haw...der_mites_1.jpg

http://www.hort.wisc...ales/scales.htm

Keep in mind that these are photos of desperate situations (kind of like looking at full blown rickets in a child, as opposed to seeing milder, earlier symptoms. It's good to zero in by recognizing the advanced stages of a problem but you need to watch for milder, subtler signs if you hope to nip the trouble in the bud.
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