Dr. George Ray McEachern (TAMU) says: Varieties will continue to change. Pecan trees are prone to fungus diseases such as scab, powdery mildew, crown gall and wood or heart rots, according to the North Carolina Cooperative Extension Service. For registration information, contact Texas A&M AgriLife Conference Services at https://agriliferegister.tamu.edu/ or (979) 845-2604. Wind and rain spread spores of the disease organism. – Pruning Domestication of pecan began in the late 1800’s and much genetic potential remains to be capitalized upon. Physiological, nut drop, variety reaction – Shuck die back (Physiological – possible hormone imbalance) is commonly associated with Success and Success hybrids. Later in the season, lesions turn brown due to the death of leaf cells in the disease area. – Pink mold (Secondary diseases, behind scab lurks pink fungus) Mycoplasm, sucker growth – Bunch disease (Mycoplasm) – Evidence indicates it is a mycoplasm [bunchdis]. Crop sanitation Experiments for the Control of Pecan Scab Disease.. Texas Agricultural Experiment Station. This family includes the walnuts and the hickories. The fungicides labeled for control of pecan scab on bearing trees are not available in small quantities marketed for backyard trees. 12). By mid-summer, black pimple-like dots become especially noticeable in the leaf spots after the surface spore masses have been removed by wind and rain giving the diseased areas of the leaves a black, shiny appearance. Few native groves are sprayed for anything other than weevils and pecan nut casebearers. (even susceptible cultivars like Wichita can be planted). No long term yield data is available. Scab disease is most damaging to pecan trees grown east of central Texas. The following 8-spray fungicide schedule is provided as an example of one option to use for pecan scab management in light of the emerging scab insensitivity issues surrounding some of our fungicides. – Shuck die back ( Physiological, nut drop, variety reaction) ble to the pecan scab fungus during this period. 11-11:30 a.m. – Pecan scab and bacterial leaf scorch update, Young-ki Jo, Ph.D., AgriLife Extension specialist in plant pathology and microbiology, College Station. infections occur (e.g. Do not rely on aerial Scab is a fungus which invades the young rapidly growing shoots and leaves and later the developing nuts. Even when sound cultural practices are followed, producers may need to apply a protective fungicide in some locations and on scab-susceptible cultivars. Secondary diseases, behind scab lurks pink fungus – Pink mold (Fungus – Trichotecium roseum) usually occurs on nuts infected with scab fungus. Shallow disking or removal of the old plant debris will help to reduce the amount of fungal pathogens and insects present in a grove. little scab on the nuts and rainfall is sparse. The long cycle time for pecan trees plus financial considerations dictate that new varieties go through an extensive vetting process before being widely planted. These spores are spread by wind and rain to newly developed leaves where they germinate and invade the tender tissues, initiating primary infection. When the disease is severe, infected leaflets are killed causing defoliation of the trees in late summer or early fall and resulting in reduced tree vigor and increased susceptibility to invasion by other pathogens. Late season, defoliation, weak trees – Brown leaf spot (Fungus – Cercospora fusca) affects only mature leaves [brwnlfsp] and usually does not appear until mid-June or July. The Texas A&M Department of Horticultural Sciences offers two undergraduate and three graduate degrees that prepare students for a myriad of diverse career opportunities.. Our mission is to: Because rain and high humidity increase scab infection, pecan scab is more severe in Central and East Texas. – Bunch disease (Mycoplasm, sucker growth) Primary scab lesions commonly occur on or along the leaflet veins but may be found between the veins. In areas where a spray program for the control of scab is carried out, leaf blotch usually is not a damaging absence of other pecan diseases, two applications of fungicides will control the disease effectively. Primary infection of new leaves in the spring occurs from spores produced in old, overwintered leaves. 1-1:15 p.m. – Texas Pecan Growers Association announcements, Blair Krebs, TPGA executive director, Bryan. Desirable 2010, 2011, cv. White powdery fungus, high temperatures, dry conditions, immature foliage – Powdery mildew (Fungus – Microsphaera alvi) – When pecans become infected with this fungus [powmil], they appear to be covered with a white, powdery material. Some pecan scab resistant cultivars recommended for the home planting include Amling, Adams 5, Miss L, Prilop, Kanza, Headquaters, and Gafford. Fungicides and fungicide application costs are becoming a major part of the pecan production program. It is difficult for homeowners to properly manage pest problems so that large pecans can fill out properly. Lesions resulting from these infection sites become visible to the naked eye within 7 – 9 days depending on environmental conditions. Comparison of different areas of Texas using days above 90 deg. It has also been associated with young trees at the graft union and on older trees where limbs are pruned out. Another reason to concentrate on insect control is the fact that pecan fungicides are available only in commercial-size packages. These lesions may enlarge and coalesce, or come together, enveloping the entire leaflet and causing the leaflet to … Symptoms include black lesions and tissue death on twigs, leaves, and nuts from early spring until late summer (Fig. Scab is most severe during times of above-average rainfall. Leaves which are severely affected drop resulting in premature defoliation. If used properly, fungicides can prevent significant losses to disease. Honeydew sooty mold – The development of damaging populations of yellow aphids varies with the part of the country we are talking about.