Epidemiology and pathogenesis of mycelial soil borne Rhizoctonia solani AG 3 on potatoes (Solanum tuberosum)

This thesis describes aspect of the epidemiology and pathogenicity of the soil-borne phase of Rhizoctonia solani AG-3 (Kuhn) fungus on potatoes and its competitive saprophytic colonisation ability in the soil. Under controlled environmental conditions, stem canker incidence and severity increased with increasing levels of soil-borne inoculum but plateaued after ¼ inoculum level (i.e 1 Petri dish of R. solani  AG-3 per kg soil).  Up to the 1/20 inoculum stem canker occurred at a low level.  A significant increase occurred at 1/10 and 1/8 inoculum levels.  A similar pattern was observed for the competitive saprophytic colonisation ability of the fungus.  The fungus was attracted more by seed tubers than by stems and the incidence of black scurf was higher than stem canker at all inoculum levels tested.  Sclerotia developed on seed tubers even at low inoculum levels.  Favourable soil conditions for infection on stems and seed tubers were 10oC and soil moisture content of 40% water holding capacity.  Optimum moisture content for saprophytism was between 20-50% water holding capacity, although optimum levels of the individual soils tested varied.  Pot and laboratory experiments indicated that conditions for development of R. solani were more conducive in heavy than in light textured soils.  When fine sand was added in increasing quantities to a sandy clay loam soil, the disease initiated by the fungus was steadily reduced with an increase in sand content.  Potato cultivars differed in their susceptibility to R. solani at early stages of growth but  none of the cultivars tested showed complete resistance to the disease.  Depth of planting had no significant effect of Rhizoctonia stem and seed tuber infection.EThOS - Electronic Theses Online ServiceGBUnited Kingdo

Likelihood of ACL graft rupture: not meeting six clinical discharge criteria before return to sport is associated with a four times greater risk of rupture

Background: The decision as to whether or not an athlete is ready to return to sport (RTS) after ACL reconstruction is difficult as the commonly used RTS criteria have not been validated. Purpose: To evaluate whether a set of objective discharge criteria, including muscle strength and functional tests, are associated with risk of ACL graft rupture after RTS. Materials and methods: 158 male professional athletes who underwent an ACL reconstruction and returned to their previous professional level of sport were included. Before players returned to sport they underwent a battery of discharge tests (isokinetic strength testing at 60°, 180° and 300°/s, a running t test, single hop, triple hop and triple crossover hop tests). Athletes were monitored for ACL re-ruptures once they returned to sport (median follow-up 646 days, range 1–2060). Results: Of the 158 athletes, 26 (16.5%) sustained an ACL graft rupture an average of 105 days after RTS. Two factors were associated with increased risk of ACL graft rupture: (1) not meeting all six of the discharge criteria before returning to team training (HR 4.1, 95% CI 1.9 to 9.2, p≤0.001); and (2) decreased hamstring to quadriceps ratio of the involved leg at 60°/s (HR 10.6 per 10% difference, 95% CI 10.2 to 11, p=0.005). Conclusions: Athletes who did not meet the discharge criteria before returning to professional sport had a four times greater risk of sustaining an ACL graft rupture compared with those who met all six RTS criteria. In addition, hamstring to quadriceps strength ratio deficits were associated with an increased risk of an ACL graft rupture

Likelihood of ACL graft rupture: not meeting six clinical discharge criteria before return to sport is associated with a four times greater risk of rupture

Background: The decision as to whether or not an athlete is ready to return to sport (RTS) after ACL reconstruction is difficult as the commonly used RTS criteria have not been validated. Purpose: To evaluate whether a set of objective discharge criteria, including muscle strength and functional tests, are associated with risk of ACL graft rupture after RTS. Materials and methods: 158 male professional athletes who underwent an ACL reconstruction and returned to their previous professional level of sport were included. Before players returned to sport they underwent a battery of discharge tests (isokinetic strength testing at 60°, 180° and 300°/s, a running t test, single hop, triple hop and triple crossover hop tests). Athletes were monitored for ACL re-ruptures once they returned to sport (median follow-up 646 days, range 1–2060). Results: Of the 158 athletes, 26 (16.5%) sustained an ACL graft rupture an average of 105 days after RTS. Two factors were associated with increased risk of ACL graft rupture: (1) not meeting all six of the discharge criteria before returning to team training (HR 4.1, 95% CI 1.9 to 9.2, p≤0.001); and (2) decreased hamstring to quadriceps ratio of the involved leg at 60°/s (HR 10.6 per 10% difference, 95% CI 10.2 to 11, p=0.005). Conclusions: Athletes who did not meet the discharge criteria before returning to professional sport had a four times greater risk of sustaining an ACL graft rupture compared with those who met all six RTS criteria. In addition, hamstring to quadriceps strength ratio deficits were associated with an increased risk of an ACL graft rupture.Seksjon for idrettsmedisinske fag / Department of Sports Medicin