Richard

The problems could be

• burning up from over-fertilization or too much acidity
• alkaline soil
• bad fungi or bacteria on the roots

Check the pH of the soil in several places (before watering).

Remedies:

• There should be 2 inches of mulch above the soil. Use the fine-grain natural bark they sell at Home Depot in $3 bags. Don't use the mulch from the San Diego City Greenery -- it has diseases and widely varying pH. (The Greenery compost is o.k. as a soil mix though - it has been thoroughly cooked).
• Make sure that the soil in the root zone (whatever depth in the 24" box) is not soggy. If it is, then it is not time to water. Drill an access hole in the side of the box so you don't disturb other roots. Make a plug for the hole that stays in when you are not peeking at the soil.
• Make sure the 24" pot is not in direct sunlight. Shield with cardboard if necessary. If the soil in the pot is heating too much, you are "cooking" the roots.
• If the pH is under 6.0, too much acid or fertilizer might be the problem, along with infection. Add 1/4 cup of Lily Miller PolySul (Calcium Sulfide) to a gallon of water and pour it in the box evenly. PolySul is slightly alkaline (pH ~ 7.5) so it will help bring up the pH, and the sulfur will get rid of the infection. Make sure the water is on the cool side and not warm or hot. If in one week the soil is still acidic, we'll try powdered or liquid gypsum, but no more sulfur treatments for quite awhile.
• If the pH is between 6 and 7, we've got an infection. Treat with 1 ounce (2 Tbsp) of Spectracide Immunox in one gallon of water. If any fruit is on the tree or forms in the next 6 weeks, you must remove it to avoid toxicity.
• If the pH is above 6.8, then the soil is too neutral (pH=7) or alkaline (pH > 7). Add either 2 Tablespoons of granulated Sulfur or 3/4 cup of Ada Perry's Rose Food sold at Walter Andersens Nursery -- it contains sulfur and several other nutrients. The sulfur will correct the pH and kill the infection. Before adding either, scoop out the mulch, distribute the granules, and put the mulch back on top so it does not interfere with the product.

Tony, I have all of these supplies and I need to run an errand down your way in the next day or so. Let me know if you need help.

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