Acervulus

Abstract: Leptodiscus terrestris Gerd. is a common parasite of several forage legumes (5). The fruiting body of this fungus was originally described as a superficial, radiate stroma one cell layer thick, and it was considered to most nearly resemble an acervulus (4). A more detailed study has been made on the fruiting structure in an effort to determine its affinity, and the origin and development of conidia have been more thoroughly investigated. The conidia of L. terrestris have a relatively long filamentous seta at each end. A study was made to determine the position of the setae relative to the spores when the spores are contained in the spore head, and to determine if the setae function in spore dispersal. Setulate conidia are produced by many fungi; however, there are few reports in which a function has been attributed to them. Atanasoff (2) found that the bristles borne on the conidia of Dilophospora alopecuri (Fr.) Fr. became attached to the body of a nematode and that the nematode transported the spores to the growing point of cereals. Cunnell (3) found that the setae of Robillarda phragmitis were folded back against the side of the spore and that they became extended when the spore was released. He suggested that the appendages might function as a flotation device.

Abstract: The ontogeny of the sclerotia of Colletotrichum coccodes was investigated by scanning electron microscopy. The sclerotium originated as an acervulus differentiated from a stroma, a mass of tightly ...

Abstract: The testing of seeds using both the blotter and potato dextrose agar showed infection of Colletotrichum capsici to be well established both within and on the external surfaces of chilli seeds. Microtome sections showed that mycelia were present in the outer and inner layers of the testa and in the endosperm region. Formation of the acervulus was initiated below the seed coat and also in the endosperm and emerged to the surface after disrupting the seed coat. Parenchymatous tissues were also distorted. The pathogen finally grows on the seed surface.

Abstract: To investigate the primary inoculum for latent infection on strawberry (Fragaria×ananassa Duch.), healthy plants (HP) derived from tissue culture and symptomless local farm plants (LFP) were grown in a strawberry nursery field in Nonsan Strawberry Experiment Station and local farms from 2001 to 2002. Among HP, occurrence of anthracnose was firstly detected in 2.2% of daughter plants on July 10th (98 days after planting). Meanwhile, among LFP, 10% of mother plants were wilted on June 10th (68 days after planting). In local farms, anthracnose did not occur in the nursery field where HPs were planted, but anthracnose incidence in LFP were detected from 5 to 60%, based on the survey in Aug. 2001 and Sept. 2002. To detect rapidly latent infection of Colletotrichum gloeosporioides (Penz.) Penz. & Sacc. on strawberry, 5 min ultraviolet light (UV) radiation, water rinse, 30 sec herbicide paraquat (2.5mL․L^^1) treatment, and 30 sec 70% ethanol treatment were tested, respectively. Acervulus formation of C. gloeosporioides was observed on petioles treated with either UV, water, paraquat, or ethanol. However, acervulus formation were not detected in non-treatment samples. Paraquat treatment was faster than other treatments for developing acervulus of C. gloeosporioides. Rapid and accurate detection of latent infection on strawberry anthracnose should be possible effectively by paraquat treatment on petioles.