Dan's ideas · More Info

Dan's ideas · More Info

Dan's ideas · More Info

Dan's ideas · More Info

Region: Northern California - East Bay Area

Soil Type: Clay; poor drainage but drain through retaining wall

Tree Age: Tree is at least 10+yr old; it was mature when we moved into the house about 7yr ago. It was full of thick green leaves until ~2yr ago. Note, I believe we may have rust mold or powdery mildew.

Your tree appears underfed and possibly underwatered.

How much fertilizer are you applying? I aim for 3/4 to 1 pound of N for a tree that size. BTW, I've never had success with spikes.

Your tree should be getting regular water ... every two to three days a shot and every 7 to 10 days a good deep soak.

I see large trees close by,,, any chance their roots found their way to your tree? If so, you have a lot of work ahead of you.

Thanks. It gets about 3-4 handfuls of the Dr Earth Citrus every 6wks or so. Not sure the exact N content of that but will check. Water shouldn’t be an issue, but will try to up the longer soaks. It should be getting a couple gallons every 2d and a longer 20-30 gallon soak once a week. May need to dig and check how deep the drip system is getting. Definitely could be running into competing root systems with my neighbors trees. Not much I can do on that front tho.

OK, with the age of the tree the water you describe should be good enough. The leaves are rippled which confirms it getting plenty of water at some time in the past.

I believe the challenge for this tree is getting enough nutrition. The amounts I stated above are in a perfectly flat and lone planting. The amount applied needs to be bumped up for things like: wood mulch, slope, other plants / trees proximity (competing established landscaping and depleted soil), etc. Not all the fertilizer you put down will get to the target tree. Do the math and apply accordingly.

Please give an update in a month and next year - good luck!

Here is a handy reference - - I forget where it came from - sorry. [in general a cup of granular fertilizer is about 1/2 lb of fertilizer] Divide by the first number of the fertilizer by 100 to obtain your % pound of N].

Copy / pasted another reference here:

Fertilizer Guidelines
Follow the directions on the fertilizer bag carefully. Citrus fertilizers vary in the amount of nitrogen and other nutrients they contain. The label will tell you much fertilizer you need and how to apply it.
How much fertilizer to apply is based on the size and age of your tree as well as the percentage of nitrogen in the fertilizer you are using. To figure out how much to apply, follow the directions on your fertilizer package or refer to a fertilizing citrus chart. Be sure to divide by three the annual amount of fertilizer needed. Don't apply it all at once!
Lightly rake granular fertilizer into the top inch or two of soil.
Water the entire area underneath the tree before and after applying fertilizer.

I think it could be a Potassium deficiency.

Please do not use fertilizer stakes. Nitrogen in the stake moves through the soil efficiently but the phosphorous and potassium do not. They just sit there. As the roots move through the soil and encounter the spike they get burnt. The fertilizer spikes also contain salt.

For what ever reason the plant is not uptalking enough nutrients. Perhaps the roots are water logged or damaged, pH is wrong, or poor soil. A foliar spray is very important especially if the plant can not get required nutrients from the soil. Use Southern AG foliar spray.

Your soil if probably too alkaline. Check your soil pH. Do a Google image search for "ph vs availability of nutrients". Compare chart to your soil pH. What ever fertilizer you are using it is not working. Try something different like BGI citrus gain.

The picture of the leaf looks like whole leaf chlorosis caused by nitrogen deficiency. I see other types of mineral deficiency in the other picture as well. Citrus are very heavy nitrogen feeders. http://www.idtools.org/id/citrus/diseases/factsheet.php?name=Nutrient+deficiency