Marin Master Gardeners
University of California
Marin Master Gardeners

How Integrated Pest Management saved four loquat trees

loquat tree
“That’s amazing!” said our landscape contractor. “I’ve never seen anything like it,” he added, impressed by the visible difference in a loquat tree that looked destined for death only six weeks earlier. The tree was one of four loquats which we would be keeping on a waterfront berm facing Corte Madera Creek as the contractor installed new plants. Unfortunately, none of the loquats looked well – especially the one viewed from my living room window that looked sick and had been dropping leaves for weeks.

This is the story behind the loquat’s transformation. As a Marin Master Gardener-in training, I had learned about Integrated Pest Management. IPM involves knowing 1) the cultural requirements for optimum plant health, 2) common susceptibility to diseases or pests, and 3) corrective and preventive measures to take if issues arise.

Giving IPM a try, I searched on “loquat” after examining leaves and bark and collecting samples of dropped leaves from all four trees. My first reading confirmed identification and told me what was wrong: 1) The leaves and bark showed signs of a disease called fire blight, caused by the bacterium Erwinia amylovora. 2) The basic cultural requirements of loquat trees were not being met.

Using the principles of IPM, we first took corrective action to stop the spread of fire blight by disconnecting the overhead sprinkler irrigation and picking up all the fallen leaves over the course of two-three weeks. Then we took steps to meet the loquats’ cultural requirements by removing weeds growing up against the tree trunks. We mulched up to the root line (where the canopy starts), leaving a 24-inch circumference of bare soil for good air circulation. As a gift to the trees, we also put down a layer of compost at the root line to help feed the soil. We watered deeply by hand until drip irrigation could be installed to replace the sprinklers.

Weeks later, condo residents with a view of the loquats noticed the turnaround. “What a beautiful difference!” “The trees have never looked this good!” “What happened?” they asked. “IPM,” I replied. I took notice that meeting a plant’s cultural requirements does double duty — it promotes good health and good health helps prevent disease.

The critical component was taking a step back and identifying exactly what the tree needed for optimum health: less competition from weeds and overhead watering, better quality soil and air circulation. Often, when confronted with a sick or struggling plant, the first inclination is to run to the store and buy a fertilizer or pesticide or other remedy in the hope of “curing” an ailing patient. As our loquat story illuminates, this is not always what’s best for the plant – or the planet.

Months later I came across a photo of a fifth loquat, last in line on the waterfront berm, that had died before my time here. I had taken the photo before the tree was removed. I recognized that the dead tree was a textbook example of fire blight!

Thanks to IPM, we have four thriving, handsome loquats enjoyed by homeowners and birds. IPM is a gift at your fingertips, accessible all year long. All it takes is a little digging in and monitoring. But it may make a profound difference in the health and beauty of your garden for many years to come.

To learn more, visit the University of California Integrated Pest Management page.


By UC Marin Master Gardener Rosaline Huang Gould

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