Pleospora bjorlingii. [Descriptions of Fungi and Bacteria].

Author(s):  
C. Booth

Abstract A description is provided for Pleospora bjorlingii[Pleospora betae]. Information is included on the disease caused by the organism, its transmission, geographical distribution, and hosts. HOSTS: On Beta spp. DISEASE: Black leg of sugar beet and mangold. Also root rot and leaf rot or heart rot (45, 1243), storage decay (41: 188) and clamp rots (45, 2655). GEOGRAPHICAL DISTRIBUTION: Africa (north & south); Asia, Australasia, Europe, N. America. (CMI Map 427, Ed. 1, 1967). TRANSMISSION: On seeds and in decayed host material or soil.

Author(s):  
J. A. Lunn

Abstract A description is provided for Rhizopus oryzae. Information is included on the disease caused by the organism, its transmission, geographical distribution, and hosts. HOSTS: In air, soil, compost, and pathogenic for plants, man and other warm blooded animals. DISEASE: Plants: Often in association with R. stolonifer or other fungi, causes pale brown soft rot of fruit, vegetables and bulbs, especially rot of sweet potatoes (Harter et al., 1921; Lauritzen & Harter, 1925; 52, 4179 (as R. nodosus)), root rot of sugar beet (Hildebrand & Koch, 1943; Gaskill & Seliskar, 1952; 52, 1718) and seed-bed losses in groundnuts (Gibson & Clinton, 1953). Also, again in association as above, causes storage rot of many plant products (53, 99) including soyabean seed (54, 1959). Man and animals: Cause of rhinocerebral phycomycosis, sometimes with ocular or vascular involvement in man, particularly diabetics (RMVM 6, 504, 3028; 5, 1426; 8, 2113; 9, 2410). Also reported from bovine mycotic abortion (Nicolet et al., 1966) and from mycotic pneumonia in chicks (RMVM 7, 1861). Has been used in experimental infection of mice, thyroidectomized rats (RMVM 6, 2119) and alloxan-diabetic rabbits (RMVM 7, 2628). GEOGRAPHICAL DISTRIBUTION: World-wide. TRANSMISSION: By air-borne sporangiospores.


Author(s):  
G. Hall

Abstract A description is provided for Pythium acanthophoron. Information is included on the disease caused by the organism, its transmission, geographical distribution, and hosts. HOSTS: Ananas sativus, Brassica chinensis, Cicer arietinum, Daucus carota, Eucalyptus regnans, Gossypium sp., Larix sp., Lolium perenne, Phaseolus vulgaris, Pinus sp., Trifolium subterraneum. In artificial infections: Absidia glauca, Basidiobolus ranarum, Entomophthora coronata, Fusarium solani, Mucor hiemalis, Pythium myriotylum. Also in soil around ginger and bedding plants, and in sand dunes. DISEASE: Leaf rot of pineapple, root rot of beans (61, 3765), and a range of other non-specific root rots, although the fungus seems only weakly pathogenic to most plant hosts; a facultatively necrotrophic plant pathogen and also a mycoparasite. It seems to have a more important role as a mycoparasite, particularly of Zygomycetes, and may be present around roots, parasitizing root infecting fungi. GEOGRAPHICAL DISTRIBUTION: Asia; China (Guangdong), India, Japan, Philippines. Australasia & Oceania; Australia (Vic., WA). Europe; UK (Scotland, Wales). North America; USA (Hl). TRANSMISSION: Presumably by mycelial growth in moist infected soils. Oospores and zoosporangia have been shown to survive in soil rather than in plant debris (62, 802), and serve as perennating structures. Oospores may be dispersed by wind from dry soil.


Author(s):  
J. E. M. Mordue

Abstract A description is provided for Glomerella cingulata. Information is included on the disease caused by the organism, its transmission, geographical distribution, and hosts. HOSTS: Reported frequently an Annona, apple, avocado, banana, cacao, Camellia, Capsicum, cherry, citrus (grapefruit, lemon, lime, orange), coffee, lupin, mango, papaw, pear, Piper, rubber, tea, tomato, vine, yams; also on many other cultivated and wild plants. DISEASE: Anthracnose of stems and leaves, dieback, root rot, leaf spot, blossom rot, fruit rot (dieback and ripe rot), seedling blight. GEOGRAPHICAL DISTRIBUTION: World wide, though more abundant in tropics and subtropics than in temperate regions. TRANSMISSION: Persists on and in seed, trash and weed hosts and is dispersed locally by water splash, air currents, insects or other form of contact. Frequently isolated from soil.


Author(s):  
E. Punithalingam

Abstract A description is provided for Ascochyta desmazieresii. Information is included on the disease caused by the organism, its transmission, geographical distribution, and hosts. HOSTS: Lolium multiflorum and L. perenne. DISEASE: Glume and leaf spot of Italian and perennial ryegrasses. At first leaf lesions start as small purplish or chocolate-brown spots with a distinct red-purple margin. With time these enlarge, become irregular or elliptical, up to 5 mm long and distinctly visible on both sides of the leaves. Finally the centres of older lesions fade to fawn to straw yellow with numerous pycnidia immersed within the leaf tissue on both sides of the leaves but usually abundant pycnidia occur on the lower side. GEOGRAPHICAL DISTRIBUTION: Asia (Japan); Europe (Belgium, Czechoslovakia, Denmark, France, Irish Republic, UK); N. America (USA, California, Oregon, Washington); S. America (Chile, Brazil). TRANSMISSION: No specific studies reported; infection is presumably spread by air-borne conidia in wet weather or heavy dews. The fungus is also probably carried over on crop residues and debris in soil.


Author(s):  
G. M. Waterhouse

Abstract A description is provided for Pythium intermedium. Information is included on the disease caused by the organism, its transmission, geographical distribution, and hosts. HOSTS: On a wide range of hosts represented by the following families: Begoniaceae, Bromeliaceae, Chenopodiaceae, Compositae, Coniferae, Cruciferae, Euphorbiaceae, Geraniaceae, Gramineae, Leguminosae, Liliaceae, Linaceae, Moraceae, Onagraceae, Ranunculaceae, Rosaceae, Solanaceae, Ulmaceae, Violaceae; also in the Equisetales and Filicales. DISEASES: Damping-off of seedlings, foot rot and root rot of ornamentals, occasionally of crop plants and trees. GEOGRAPHICAL DISTRIBUTION: Asia (China); Australia & Oceania (Hawaii); Europe (England, Belgium, France, Germany, Holland, Sweden, U.S.S.R.); North America (U.S.A.); South America (Argentina). TRANSMISSION: A common soil inhabitant.


Plant Disease ◽  
2016 ◽  
Vol 100 (12) ◽  
pp. 2427-2433 ◽  
Author(s):  
Sahar Arabiat ◽  
Mohamed F. R. Khan

Rhizoctonia damping-off and crown and root rot caused by Rhizoctonia solani are major diseases of sugar beet (Beta vulgaris L.) worldwide, and growers in the United States rely on fungicides for disease management. Sensitivity of R. solani to fungicides was evaluated in vitro using a mycelial radial growth assay and by evaluating disease severity on R. solani AG 2-2 inoculated plants treated with fungicides in the greenhouse. The mean concentration that caused 50% mycelial growth inhibition (EC50) values for baseline isolates (collected before the fungicides were registered for sugar beet) were 49.7, 97.1, 0.3, 0.2, and 0.9 μg ml−1 and for nonbaseline isolates (collected after registration and use of fungicides) were 296.1, 341.7, 0.9, 0.2, and 0.6 μg ml−1 for azoxystrobin, trifloxystrobin, pyraclostrobin, penthiopyrad, and prothioconazole, respectively. The mean EC50 values of azoxystrobin, trifloxystrobin, and pyraclostrobin significantly increased in the nonbaseline isolates compared with baseline isolates, with a resistant factor of 6.0, 3.5, and 3.0, respectively. Frequency of isolates with EC50 values >10 μg ml−1 for azoxystrobin and trifloxystrobin increased from 25% in baseline isolates to 80% in nonbaseline isolates. Although sensitivity of nonbaseline isolates of R. solani to quinone outside inhibitors decreased, these fungicides at labeled rates were still effective at controlling the pathogen under greenhouse conditions.


Plant Disease ◽  
2001 ◽  
Vol 85 (7) ◽  
pp. 718-722 ◽  
Author(s):  
Sebastian Kiewnick ◽  
Barry J. Jacobsen ◽  
Andrea Braun-Kiewnick ◽  
Joyce L. A. Eckhoff ◽  
Jerry W. Bergman

Rhizoctonia crown and root rot, caused by the fungus Rhizoctonia solani AG 2-2, is one of the most damaging sugar beet diseases worldwide and causes significant economic losses in more than 25% of the sugar beet production area in the United States. We report on field trials in the years 1996 to 1999 testing both experimental fungicides and antagonistic Bacillus sp. for their potential to reduce disease severity and increase sugar yield in trials inoculated with R. solani AG 2-2. Fungicides were applied as in-furrow sprays at planting or as band sprays directed at the crown at the four-leaf stage, or four- plus eight-leaf stage, while bacteria were applied at the four-leaf stage only. The fungicides azoxystrobin and tebuconazole reduced crown and root rot disease by 50 to 90% over 3 years when used at rates of 76 to 304 g a.i./ha and 250 g a.i./ha, respectively. The disease index at harvest was reduced and the root and sugar yield increased with azoxystrobin compared with tebuconazole. The combination of azoxystrobin applied at 76 g a.i./ha and the Bacillus isolate MSU-127 resulted in best disease reduction and greatest root and sucrose yield increase.


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