DISEASE: Pecan scab PATHOGEN: Fusicladium effusum (former names include Fusicladosporium effusum, Fusicladium caryigenum, Cladosporium caryigenum, and Cladosporium effusum) HOST AND RANGE: Host species include pecan (Carya illinoinensis) and other Carya species, … blotches on leaves, nut shucks. Kaufman County Texas. Attacking in wet, humid weather, the fungus covers young twigs, leaves and developing nuts with olive-brown to black spots. DOI: 10.1094/PHI-I-2016-0620-01. Pecan scab, caused by the fungus Cladosporium caryigenum, is generally the most damaging pe can disease. Thus, use a variety of fungicide groups for pecan scab disease control and make applications in a preventative manner before disease builds up to levels that will harm the crop and make control difficult. Pecan scab (PS) is the only economic disease found in Missouri orchards. Pecan scab is the most economically significant disease of pecan trees (Carya illinoinensis) in the southeastern United States. become numerous, leading to … Here's a link to the Texas Plant Disease Handbook with more information about scab and treatment. 1 Response. Pecan scab (Venturia effusa) Lifecycle of Venturiaeffusa, cause of pecan scab Autumn Winter Summer Spring Fungus becomes dormant as stroma and overwintering conidia (twigs and shucks) Epidemics build up on young leaves (conidia) Overwinters as stroma and conidia Epidemics build up on fruit (conidia) Polycyclic disease (rain and wind) We commonly get requests for a … Mason 2016. Nut losses on unsprayed susceptible varieties can reach 50 percent to 100 percent in a year. In addition, unsprayed trees prematurely defoliate, which negatively affects next season's nut crop. As of the summer of 2014, the following varieties are currently known to have the best resistance to this disease: Elliott, Excel, and Kanza. Pecan scab is widely regarded as the most damaging pecan tree disease. My pecan trees have had pecan scab for some time. These spots may have a velvety or cracked appearance. It attacks the pecan leaves, but mature leaves are safe. How can one get rid of pecan scab? Pecan scab, caused by the. Scab is the most prevalent and challenging disease to attack pecan trees. The disease can be identified by the following symptoms: They may be small, circular, or have olive-green to black spots form on the lower surface of the leaf and nuts. But getting the best use out of them and doing so in a manner that prevents resistance development can be confusing for some folks. We’re fortunate to have a wide variety of fungicide options for pecan scab management. the shade value and the nut crop. (husks), leaf blades and leaf petioles (Figures 1 and 2). Prevention & Treatment: The best way to reduce the overall impact that pecan scab will have is to plant scab-resistant pecan varieties. Leaf spots may. Pecan scab, caused by the fungus Cladosporium caryigenum, forms spots or on leaves and nut shucks, expanding as the leaves expand. Infected nuts sometimes drop prematurely. Asked December 18, 2013, 8:56 PM EST. and B.D. Scab only does damage to young leaves, from bud break until they reach maturity. Venturia effusa is a fungal plant pathogen that causes pecan scab. olive green to black sunken spots or. The Plant Health Instructor. The scab fungus forms small, circular, There are a number of important. The fungus causes lesions and tissue death on pecan twigs, petioles, leaves, nuts and shucks beginning in early spring, with multiple cycles of infection repeating until late summer. Pecan Scab. Hoefnagels, M.H. How do I get rid of it?