Effect of chemical seed treatment on the germination and seedling growth of canola under different soil conditions

Abstract

Studies in a temperature controlled greenhouse were conducted to determine if phytotoxic effects of chemical seed treatments found in incubation studies also have an effect on the germination-and seedling vigour of canola (cv Varola 44) seed planted in simulated field conditions and secondly to determine the efficiency of seed treatments in soils from different localities (naturally infested) and in soil artificially infested with soilborne pathogens. In the first experiment untreated (control) and seeds treated with 0.5X, 1.0X and 2.0X of the recommended rates of Cruiser® and a local mixture (SA-Combination) were planted at 5 and 10 mm depths in dry (10% of field water capacity), moist (50% of field water capacity) and wet (70% of field water capacity) pasteurized soil to ensure that only the phytotoxic effects of the seed treatments were measured. In general, results showed that some treatments (application rates) of both chemicals used delayed seed germination and therefore reduced the number of seedlings emerged after 9 days, especially when planted at a 5 mm depth in pasteurized dry soil, but not in moist (50% FWC) soil. In soils naturally infested with especially Rhizoctonia spp. and Pythium spp. (experiment two), seedling emergence, survival and plant height of treated seeds were significantly higher compared to that of untreated seed. In experiment three all the seed treatments significantly increased survival of canola seedlings in soil artificially infested with Fusarium avenaceum, pythium F group, P. irregulare, P. mamillatum, P. iJltimum var. ultimum and Rhizoctonia spp. under growth room conditions. Survival of seedlings was a more accurate or sensitive parameter than dry mass when evaluating the effect of seed treatments against damping-off of canola caused by these soilborne pathogens. Because no consistant differences for all parameters used were found between chemicals used, both chemicals should be regarded as efficient. More research is needed to test their efficiency against specific pathogens under field conditions before any recommendations with regard to registration and commercial use in the RSA can be made.

Evaluation of strategies for the control of canola and lupin seedling diseases caused by Rhizoctonia anastomosis groups

“…However, SA-combination was more effective than Cruiser OSR in protecting canola seedlings against AG-2-1 and AG-4. Researchers in Canada and Australia have reported iprodione (included in SA-combination) to be effective for control of R. solani in canola (Kataria and Verma 1993;Khangura, et al 1999). De Villiers et al (2006 evaluated Cruiser OSR and SA-combination [with imidachloprid (Gaucho) added] against damping-off of canola caused by uncharacterized Rhizoctonia isolates.…”

“…difenconazole, fludioxonil, metalaxyl-M, thiamethoxam) and SA-combination (a.i. iprodione, metalaxyl, thiram) tested by De Villiers et al (2006) were evaluated for their capacity to control seedling damping-off. The SAcombination formulation used in this study differed from that used by De Villiers et al (2006) in that it did not include the insecticide Gaucho (imidachloprid).…”

“…iprodione, metalaxyl, thiram) tested by De Villiers et al (2006) were evaluated for their capacity to control seedling damping-off. The SAcombination formulation used in this study differed from that used by De Villiers et al (2006) in that it did not include the insecticide Gaucho (imidachloprid). Seed of the canola cvs Muster, Rocket and Thunder and lupin cvs/selections Cedara, E82.1.1 and Mandelup were treated with either Cruiser or SAcombination.…”

“…A complex of organisms viz., Fusarium, Pythium and Rhizoctonia spp. were shown to be responsible for damping-off and contributed to poor crop establishment (De Villiers et al 2006). Recently, Tewoldemedhin et al (2006) characterized the Rhizoctonia AG isolated during three growth seasons (2000)(2001)(2002)(2003) from canola and lupin as well as from the plant species used in rotation systems with these crops in the southern production area of the Western Cape.…”

Effect of cropping system on composition of the Rhizoctonia populations recovered from canola and lupin in a winter rainfall region of South Africa

“…A complex of organisms, viz. Fusarium, Pythium and Rhizoctonia spp., were shown to contribute to poor establishment of these crops in the Western Cape region (De Villiers et al 2006). However, the composition of the Rhizoctonia spp.…”