I've been reading everything I can find on this and the Citus Growers Forum, but obviously from the state of my Mexican Lime, I am doing something terribly wrong. I've been waiting until the top 3-inches are dry before watering, well. The soil drains superbly. I live in Scottsdale, AZ - it's in a container on my patio - it's hot / 100+ the past week or so - and windy lately (for AZ). I don't know if I've over-watered, under-watered, or of something else is getting at my tree. I did not even notice the specks on the underside of the leaf in daylight, but only after I uploaded the photo and viewed it...
Carl it just looks like the normal oil glands,common to all citrus leaves. This is where much of the essential oil is located.- Millet
Hi Millet, As always I am profoundly amazed by your generosity and patience. I am very concerned about the yellowing / browning condition of the leaves and thought perhaps those spots on the underside was some parasite? You are right though... citrus are challenging.
Carl what is the formulation of the fertilizer, and what is the fertilizer schedule you are following with the tree? Does the fertilizer that you are using also contain trace minerals? Lastly, what PPM are your feeding. You should be feeding 250 - 300 PPM with each application. How tall is the tree and in what size container. - Millet
I've been using Miracle-Gro 24-8-16 water soluble plant food. The package says it also contains Boron, Copper, Iron, Manganese, Molybdenum and Zinc (trace minerals?). PPM I will have to admit to being ignorant of what I have been, or what I should be providing, nor any idea of how to calculate the proper ratio. About once every 2-weeks I mix according to package instructions (1-tbsp per gal) - I use a 2-gal watering can. Then I water until it runs out of the drains holes. I have this Mexican Lime and 2 Dwarf Navels, in progressively larger containers, which are showing some of the same signs though much less so. The Mexican Lime is in a 10" plastic container that is 12" tall. The tree is 24" tall and about 18" across. The label says it is Flying Dragon rootstock. It is growing in the medium that it was purchased in (purchased around mid April) which comes up to within 2-inches of the top of the container. I haven't repotted because I felt it might not be a great idea during the blistering heat we get here in Scottsdale, AZ. I was planning to wait until early fall or early spring to re-pot.
The tree looks quite healthy to me. Is it in full sunlight? The brown spots may be sunburn. try giving it slightly filtered light, especially if it was recently moved outdoors.
Karl, your fertilizer schedule seems to be adequate. From looking color of the leaves and the burnt tips and margins, I would say that a build up of soluble salts is developing in the growth medium. You can take care of this by giving the container a good flush with clean clear water in the amount of 4 time the volume of the container. This will flush out the soluble salts. Is Scottsdale's water hard water? Also, do you use a soft water system on the water you are irrigating the trees with?. As your fertilizer does not contain magnesium, you will have to add it separately. Magnesium Sulfate (Epsom Salts) is a good source of magnesium. Add 1 teaspoon per gallon of WARM water. Epsom Salts does not dissolve well in cold water. Apply this with every 3rd or 4th fertilizer application. Post a picture of this tree again around the first of August. Take care, and have a great summer. - Millet
I think I may have over done it with the Epsom Salts... about 2-weeks ago I applied some, only the package I have suggested 1-tablespoon per gallon as opposed to your suggestion of 1-teaspoon per gallon. Of course I used cold water, so I am sure it probably did not dissolve well, and I am sure I only compounded the problem by watering the foliage too. Do you think this might explain the yellowing and the burnt leaves? Should I wait for the soil to dry out or should I get after flushing it out first thing tomorrow AM? Thank you again.
Well, I gave my trees a good flush - but believe I will do so again in a day or two, just to make sure - though how soon again I should fertilize remains a mystery to me... My little trees were doing so well before that darned Epsom Salt, I just hope I haven't ruined them.
You can again start your fertilizer program the next time your trees require irrigation. If a problem has to develop with your containerized citrus trees, this is the best time of year for it to happen, as citrus do the majority of growth during this season of the year. They should do fine. - Millet
Thank you, Millet, I read somewhere that Citrus stops growing above 95 degrees farenheight - if if that is true it will be a couple of months before I see growth again... At the first break in the heat I will repot the Mexican Lime to a more suitable container - I hope I can time it right. The Mexican Lime seems to have born the most damage from the overdose of Epsom Salt; the two Dwarf Navels much less so. All-in-all maybe not so devastating a mistake, and one more lesson of many that I presume are coming. Thank you again.
Quick Karl, Another method of flushing is soaking your container citrus over night in a fresh water. I do this by placing the container citrus in a larger container and fill it with fresh water until it is near the top rim of the container citrus. In the morning do as Millet wrote and flush 3-4 times. Salts can become hard over time, this method works well to loosen them. The lack of aeration to to root system for a short time will not hurt citrus.
I'd be careful doing that. Many years ago, before I got serious about citrus, I had a seedling tree that went too long without water; the media was quite dry so I placed the container in the bathtub with a few inches of water and left it for several hours. That was the end of that tree. Perhaps the water I used was too warm but I'd be careful.
Jim, A healthy well care for tree with good drainage should do fine without any harm. a seven hour soaking should not harm citrus, It's the lack of O2 over a period of several days that will hurt. This method is used to remove salts from the soil.
I'm good with the flushing - I used Millet's formula of 4-times each container capacity and followed-up 2-days later with another partial flush just to make sure. Surprisingly the 2 Dwarf Navels seem to have responded very well, and very quickly, though I believe I will lose some of the older leaves. The Mexican Lime also seems to have responded positively but it looks like it will lose quite a few leaves though none of the newest growth seems to have been affected. I am still wondering if it is true that Citrus stops growing when the temperature exceeds 95-degrees Fahrenheit.
I've read that photosynthetic activity and root growth is restricted at 35C/95F and beyond. I believe, however, that limit applies to leaf surface and root temperatures rather than the ambient air temperature.
Citrus stops growth at temperatures below 55.4F and at temperatures above 95F. The prime temperature range for citrus growth is between 73 to 86F. However, citrus can survive temperatures well into the 100's. The main portion to protect when temperatures become hot is the root system, especially if the container is black. When the container is setting directly in the sun the root zone temperature can quickly reach 120F and above. These type of temperatures can kill the root system near the containers edge. Many people paint their containers white to help keep the root zone as cool as possible. Many of my containers are painted white on one side, and remain black on the other side. This way during the summer I can turn the white side towards the sun, and during the winter I turn the back side towards the sun.- Millet
Junglekeeper, I think you got it right for high temperatures. We can still get flushes of new growth out here where I am in 95-100 degree outdoor weather both for in ground and containerized Citrus. It is bottom heat that causes the slowdown in growth such as having containers placed on the ground as opposed to containers placed on concrete. The trees of ours that are on the ground, in ground trees as well, are pretty much all are covered with new growth, whereas the trees of ours that we have placed on a concrete slab are experiencing a slowdown in their new growth production. When the nighttime lows are in the 90's at midnight (extreme conditions for container Citrus) we will see no new growth from the trees that have been placed on the concrete but we can still see new growth on some of the other Citrus that are on the ground with the same high-low temperatures, albeit at a noticeable reduced rate of growth until the plants have better adapted to those conditions. Yesterday, I gave all of the container Citrus at the misses home a doze of Epsom salt prior to 100 degree conditions (I believe we had a high temperature of 111). Here is how I do it. I sprinkled on top of the soil line four ounces of Epson salt for every fifteen gallon container, which was 50 Citrus trees. Spread the crystals in a circular fashion about 4 inches away from the base of the tree right on top of the soil and waited about an hour before I came back in with a hose applied supersaturation. I applied the Epsom salt at 9 in the morning and by 10 I was watering. As a standard rule I use one ounce of Epsom salt per five gallon container (dont have any five gallon Citrus at the moment) and usually two ounces per fifteen gallon container. I in effect doubled that amount for each of the Citrus due to this being the first application this year of Epsom salt, to which the next application if need be will be back to two ounces again. Use no more than one ounce for recent transplanted trees. Many of the misses Citrus trees have been in fifteen gallon cans for two years. Anything less than a full year in the fifteen gallon can get no more than two ounces of Epsom salt per application. The thinking I use is similar to what Millet proposes to dissolve Epsom salt in warm water prior to applying it to indoor grown plants. I like dissolving Epsom salt in water when I use a liquid fertilizer as well. Done this for years for container Camellias, Azaleas and Magnolias when I want to give them a quick shot of Magnesium in this kind of heat. Latent heat from the outside temperatures as well as heat and moisture in the top soil with the crystals being exposed to hot to warm air will aid in dissolving the Epsom salt quicker than applying Epsom salts to a container plant in warm conditions with a dry soil. I do not like even applying a liquid fertilizer to a Deciduous Magnolia or a Camellia when the soil is dry. What I do is give the plant a drink of water, just a quick flash of water and then wait two or three days and then apply the liquid fertilizer for outdoor container plants or cedar box container grown trees. Jim
