Factors that affect tree scaffolds were prominent in the discussions by three farm advisors in a presentation entitled “Common Issues in the Orchard” at the 38th annual Almond Industry Conference held in Modesto in December. The farm advisors, representing the newest talent in the UC Cooperative Extension system, gave the audience valuable insights into problems they found most common in the 2010 growing season.
Leading off was Carolyn DeBuse, farm advisor for Solano and Yolo Counties. She observed a very high incidence of Verticillium wilt this past season, especially in young orchards. Certain scaffolds within the tree are affected, but most will leaf out later if left alone, she said. “Patiently wait it out,” she recommended. “Don’t cut out affected scaffolds until the following winter.” The problem occurs most often in new orchards that are planted into ground where row crops such as tomatoes grew previously. These crops are host to the Verticillium pathogen.
A second problem DeBuse observed is wind damage, causing loss of scaffolds in second-to-fourth–leaf trees that have been long-pruned and are located in extremely windy areas. “Short pruning will reduce wind breakage, as will tying,” she said.
Merced County farm advisor David Doll reported that scaffold issues were the most common reason for farm calls by almond growers in his area. Scaffold pathogens such as Ceratocystis canker, band canker and aerial Phytophthora, along with some newly identified pathogens, can result in limb loss. Most are associated with shaker damage and pruning wounds. There are no treatments for these diseases; preventive actions include avoiding tree damage.