Pear Texas Rot: How To Treat Pears With Cotton Root Rot

The fungal disease called pear cotton root rot attacks more than 2,000 species of plants including pears. It is also known as Phymatotrichum root rot, Texas root rot, and pear Texas rot. Pear Texas rot is caused by the destructive fungus Phymatotrichum omnivorum. If you have pear trees in your orchard, you’ll want to read up on the symptoms of this disease.

Cotton Root Rot on Pear Trees

The fungus causing cotton root rot only thrives in regions with high summer temperatures. It is usually found in calcareous soils with a high pH range and low organic content. The fungus causing the root rot is soil-borne, and natural to the soils of the southwestern states. In this country, these factors -- high temperatures and soil pH -- limits the geographic spread of the fungus to the southwest. The disease can attack many plants in this region. However, damage is only economically important to cotton, alfalfa, peanut, ornamental shrubs, and fruit, nut, and shade trees.

Diagnosing Pears with Cotton Root Rot

Pears are one of the tree species attacked by this root rot. Pears with cotton root rot begin to show symptoms in June through September during periods where soil temperatures rise to 82 degrees F. (28 C.). If cotton root rot on pears is found in your region, you need to be familiar with the symptoms. The first signs you may notice on your pears with cotton root rot are the yellowing and bronzing of the leaves. After the leaf color changes, the upper leaves of the pear trees wilt. Soon after that, the lower leaves also wilt. In the days or weeks after, the wilt becomes permanent, and the leaves die on the tree. By the time you see the first wilting, the cotton root rot fungus has extensively invaded the pear roots. If you try pulling out a root, it comes out of the soil easily. The bark of the roots decays and you can see woolly fungal strands on the surface.

Treatment for Cotton Root Rot on Pears

You can read up on different ideas for management practices that may help reduce the occurrence of cotton root rot on pears, but none are very effective. While you may think that fungicides would help, they actually don’t. A technique called soil fumigation has also been attempted. This involves using chemicals that turn into smoke in the soil. These also have proven ineffective for controlling pear Texas rot. If your planting area is infected with the pear Texas rot fungus, your pear trees are not likely to survive. Your best bet is to plant crops and tree species that are not susceptible to the disease.

Teo Spengler

Teo Spengler has been gardening for 30 years. She is a docent at the San Francisco Botanical Garden. Her passion is trees, 250 of which she has planted on her land in France.