I have a 4-5 year old indoor grapefruit grown from a seed. For the last couple years it has had a lot of trouble growing new leaves. It flushes vigourously every month or so but most (90%) of the new growth dries up, shrivels up, just can't get started. Occasionally larger leaves will also wither. I repotted to coconut husk and peat last year (as per this forum) and fertilized. At the time of repotting, the roots looked very healthy:white and firm. Repotting seems to have invigorated the plant but the withering continues. I did find what seemed to be reddish spider mites and webs under some leaves and I thoroughly eradicated them with q-tips and alcohol. But perhaps they are back and I can't see them? Is a systemic a possible option? I have been very diligent in spraying with soapy water, all to no avail. about to give up on this one...
spiderman, Don't give up...When was the last time you flushed the container with fresh water and rehydrated the CHC?
The type of problem you describe certainly sounds very much like the damage spider mites cause on new growth. However, you have been spraying, so I don't know if your tree has mites or not. Anyway, forget Q-tips and alcohol, that is the least successful method of eradicating spider mites. My recommendation is horticultural oils. Horticultural oils are completely non-toxic, very save to use on citrus. A horticultural oil such a Ultra Fine will completely free the tree of spider mites, aphids, and mealy bugs. Spray the branches, and both the upper and lower leaf surfaces. NOTE: Never spray a citrus tree during the heat of the day. Always spray either in the very early morning, or better yet near sundown. Another, thought that you might give some attention, and that is, the CHC growth medium. When you water the container, does the water flow through at a fast rate, so that the chips do not have time to fully hydrate? New foliage have a much higher transpiration rate then does the older mature growth, therefor, the new growth has a greater need for a continuous water supply. If the growth medium is not fully absorbing enough water, you can easily soak the growth medium by placing the tree in a larger container that is filled with water. It would only take two minutes to recharge the CHC. Good luck to this tree. - Millet
thanks to both of you. as for the CHC: it is dense enough to hold moisture for (at least) a couple of weeks. Since transplanting to this medium, I am watering according to the weight of the pot. I do seem to have overwatered at times as I adjust to the medium--there have been a couple browned out leaves. I have been bottom watering, ie. soaking the pot in a large bowl of water. I am an amateur but it does seem to me that it must be a bug, whether I can see it or not. As for oils, I have NEEM on hand. Is this ok for citrus? I burned a jade plant badly with neem. Does anyone know where I can get a useful oil in Toronto? many thanks for your suggestions. I truly hate give up! sp.
In using CHC and Peat for citrus, I would like to suggest that using this mix may need adjustments, There is no given rules on the amount of peat added to CHC. only suggested finding in growing in this mix which I view as a basic starter mix, Using CHC an Peat together is a big plus for container growers. Depending on the rootstock an climate. this mix may need more peat.
I would never use Neem oil on a citrus tree. First, Neem does not have a pleasant aroma, but second Neem Oil frequently burns the foliage of citrus trees. The two brand names of high quality horticultural oils are Ultra Fine, and Volk. Both are normally sold in pints and gallons. Of the two, I much prefer Ultra Fine Oil. You should easily be able to locate Ultra Fine Oil at almost any better Nursery, or at most big box stores, such as Home Depot, or Wall Mart (at least in the USA, and I presume also in Canada). Make a solution of 1 percent oil, and 99 percent water (This rate should be on the label). Horticultural Oils are BY FAR the No. 1 insect control chemical used world wide by the hobby and commercial citrus industry. - Millet
One further comment. Although, Coconut Husk Chips are in my estimation one of the finest growth mediums for containerized citrus, as with all mediums they have a useful life. Coconut Husks usually last at least twice as long as any of the other growth medium. Normally, a citrus tree has to be re-potted once a year when using chips such as pine, or any of the conifers. Trees grown in CHC should be re-potted approximately every 3 years (depending on the container size). I like to re-pot my citrus trees (125) early in the spring at the end of the second year's use. The most important ingredient in the container is oxygen. As a medium degrades, the oxygen level is constantly being reduced, and at the same time the CO2 (given off by the root system) increases until it begins to reach toxic levels. If your tree has not been transplanted in a long while, you should to do so. - Millet
Millet, thanks so much for all this very useful information. I will look for some oil this weekend and let you know how it goes. I am guessing that I'll spray a few times over a couple months? sp.