From Brown Tips to a Green Flush: How Our Fuerte Tree Bounced Back

Can an avocado tree recover from brown leaf tips? Ours did. Earlier in the season, a lot of our leaves had crispy brown tips, which usually means too much salt. We adjusted our watering schedule and did a gypsum treatment, and this spring the Fuerte tree in the video pushed out a beautiful green flush with no brown tips at all.

It is a small win, but it is one we worked for, and after a lot of research and trying different things it was satisfying to see the tree respond.

What brown leaf tips usually mean

When the very tips and edges of avocado leaves turn brown and dry while the rest of the leaf stays green, salt is the usual suspect. Avocados are sensitive to salt, and especially to chloride. The tree moves water to its leaves, the water evaporates, and salts carried with it collect at the ends of the leaf, where they burn the tissue. Avocado Production in California: A Cultural Handbook for Growers, Book Two, describes the pattern: chloride builds up in the leaves over the season, and once it passes about 0.25 percent of the leaf, the tissue starts to die, usually showing in September and October. Burned leaves drop, and the tree has to push out a replacement flush in late winter and early spring, just when it should be flowering, so severe tip-burn can cost yield for at least two years. The handbook is blunt that tip-burn is not a nutrient deficiency, so more fertilizer will not fix it.

Salt builds up in the root zone over time, from irrigation water, from fertilizer and manure, and from seasons with little rain to wash it through. The handbook tells growers to pay extra attention to leaching when irrigation water carries more than about 100 ppm of chloride or sodium. It is not the only cause of brown leaves, so it is worth ruling out other things; our guide to reading avocado leaf health covers the other suspects.

What we changed

Two things, together:

• Our watering schedule. We changed how we were irrigating. In general, watering deeply enough to push water past the roots is how growers carry built-up salt down and out of the root zone. The handbook calls for “conscientious irrigation and regular leaching,” and notes that in California, water stress almost always leads to chloride tip-burn, so letting trees go dry makes the problem worse. The Book Two irrigation chapter goes further: leaching is the only way to reduce salt in the root zone, and about 10 percent extra water with every irrigation is probably enough on district water.
• A gypsum treatment. Gypsum is calcium sulfate. The handbook recommends leaching plus gypsum where tests show a high sodium adsorption ratio (SAR above about 6), because the calcium helps displace sodium so water can carry it away. Gypsum spread under the canopy is also part of the handbook’s program against Phytophthora root rot, at perhaps 25 pounds beneath a medium-size tree.

Neither is a magic fix on its own. The gypsum helps the soil give up the salt; the water is what actually carries it away. For more on how we think about getting the amount right, our water hub on how much water an avocado tree needs is the place to start.

What the green flush tells us

Old leaves that already have brown tips will not turn green again. The proof is in the new growth. So the thing we were watching for was the flush, the burst of new leaves a healthy avocado tree puts out, and whether those leaves came in clean.

They did. Fresh green growth, no brown tips. It tells us the tree is healthy this year and the changes did what we hoped. If your tree is struggling more broadly, it may be worth looking below ground as well; we walked through that in diagnosing root compaction and soil stress.

Learning as we go

We did not know any of this when we inherited the grove. Every fix like this one comes from reading, asking questions, trying something and waiting to see what the tree says. When it works, it is one of the most rewarding parts of the job.

Healthy trees mean better fruit. Our 4lb Hass box and 6lb Hass box and our 4lb Fuerte box ship free in season, picked the week they go out, with a waitlist on each page between harvests. Until the trees are picking again, the avocado scoop, the Hawaiian shirt and our hats ship year-round.

Try this: If your leaves have crispy brown tips, look at your water before you look for pests. Salt is the usual cause and the cheapest thing to rule out.

This post is part of our guide to growing avocado trees.