Search Results

You are looking at 1 - 10 of 1,816 items for :

Clear All

quantities ( Kiely, 1948 ; Tran et al., 2017 , 2018 ; Wang et al., 2016 ). Fruit are most susceptible to infection up to 16 to 28 weeks after flowering, when the fungus colonizes the rind and remains latent as a knot of mycelium beneath the cuticle

Open Access

deformed leaves, stems, and petioles. Aecia produce chains of aeciospores that are wind-blown to the alternate host, a Carex species ( Mims, 1981 ). After germination and subsequent infection of sedge leaf tissue in the summer, uredinia form on the

Free access

the citrus plant causing root rot, gummosis, and foot rot of the trunk; damping-off of seedlings; leaf blight; and brown rot of fruit. The use of resistant rootstock is an effective way to control Phytophthora infection. Quantitative evaluation of

Free access

Mexico, Arizona, and California ( Graham and Gibson, 2005 ). Commercial pecan production also occurs in Mexico, South Africa, several South American countries, and Australia ( Geisler, 2011 ). Pecan is susceptible to infection by X. fastidiosa ssp

Free access

tomato ( Solanum lycopersicum ), to study the resistance of plants to infection by pathogens ( Edgar et al., 2006 ; Mandal et al., 2009 ). F. solani is one of the pathogens that has been proven to cause ARD ( Wang, 2018 ). Despite this, there is little

Open Access

Polyphenols were analyzed in expanding buds and developing leaves of pecan [Carya illinoensis (Wangenh.) C. Koch] cultivars with varying responses to Cladosporium caryigenum (Ell. et Lang. Gottwald), the organism causing scab. Plant tissue extracts were examined by high-performance liquid chromatography using a water: methanol gradient to separate polyphenolic components on a C-18 reversed phase column. A diode-array detector was used to identify profile components by retention times and computer matching of ultraviolet spectra to standard compounds in a library. Concentrations of these polyphenols were compared throughout the growing season in leaves of pecan cultivars with low (`Elliott'), intermediate (`Stuart'), and high (`Wichita') susceptibility to scab; during susceptibility to infection by Cladosporium caryigenum from 16 cultivars; and in `Wichita' leaf discs with and without scab lesions. The major polyphenolic constituent of tissues for all cultivars was identified as hydrojuglone glucoside, which was detected in intact buds and leaves throughout the growing season. Hydrojuglone glucoside concentration increased concomitantly with leaf expansion and then declined slowly. Juglone was barely, if at all, detectable, regardless of leaf age. No correlation was found between cultivar susceptibility to pecan scab and the levels of either juglone or hydrojuglone glucoside in the healthy leaves of 16 cultivars. Leaf tissue with scab lesions had significantly higher juglone and hydrojuglone glucoside levels than leaf discs without scab lesions. Chemical names used: 4-8-dihydroxy-1-naphthyl b-d-glucopyranoside (hydrojuglone glucoside); 1,5-hydroxy-naphthoquinone (juglone).

Free access

practices on the infection of sweet cherry by P. clandestina on sweet cherry. We evaluated mildew severity as a response to three training systems, four rootstocks, and five cultivars. Materials and Methods Two orchards (Hazel Dell and the Cemetery Block

Free access

galls (jiaobai) in Z. latifolia . Normal jiaobai (edible swollen galls in stem bases filled with hyphae), gray jiaobai (inedible galls filled with dark teliospores, with an unacceptable taste), and male jiaobai (without U. esculenta infection, with no

Open Access

infection is local (i.e., the host is not colonized systemically by the fungus). Plant parts (e.g., leaves, stalks, nodal shoots, tassels, ears) on which galls form depends on which meristematic tissues are active and exposed to the fungus when environmental

Free access

developing infection. Oregon currently has 1780 ha of blueberry, most of which is planted in the northwest part of the state, and produces 16,150 t of the fruit annually ( U.S. Department of Agriculture, 2007a ). Although root rot is prevalent in the region

Free access