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ARS Home » Southeast Area » Byron, Georgia » Fruit and Tree Nut Research » Research » Publications at this Location » Publication #321459

Research Project: Mitigating Alternate Bearing of Pecan

Location: Fruit and Tree Nut Research

Title: Efficacy of ProPhyt mixed with a low rate of Captec for control of peach scab in South Carolina, 2014

Author
item Schnabel, Guido - Auburn University
item Brannen, Phillip - University Of Georgia
item Bock, Clive
item Hotchkiss, Michael - Mike

Submitted to: Plant Disease Management Reports
Publication Type: Other
Publication Acceptance Date: 6/1/2015
Publication Date: 8/1/2015
Citation: Schnabel, G., Brannen, P.M., Bock, C.H., Hotchkiss, M.W. 2015. Efficacy of ProPhyt mixed with a low rate of Captec for control of peach scab in South Carolina, 2014. Plant Disease Management Reports. 9:STF006.

Interpretive Summary: Fungicides were evaluated for control of scab in a mid-ripening experimental nectarine block in Seneca, SC. Treatment regimens included: Captec 4L (two rates), ProPhyt, Captec 4L (low rate) + ProPhyt, Initiate 720 (chlorothalonil), and a non-treated control. At full maturity, 40 fruit were harvested from each plot for scab assessments (24 Jun). Scab incidence (percent infected fruit) and severity (lesions per fruit) were recorded on the day of harvest. For peach scab, a critical peak in spore production occurs during the period between petal fall and shuck split. Combinations of phosphonate fungicides, such as ProPhyt, with captan-containing products have provided synergistic and/or additive effects for management of diseases in other commodities (e.g. summer rot control in apples). A tank mix of ProPhyt plus Captec (low rate) was compared to solo applications of each and other treatments typically used by growers. All treatments provided a significant decrease in scab incidence and severity as compared with the non-treated control. There were no significant differences between fungicide treatments relative to their abilities to reduce scab as measured by severity. However, distinctions were observed for scab incidence, as a solo application of ProPhyt was less effective at reducing the incidence of scab than all other treatments with the exception of the low rate of Captec. Although numerically the best treatment, the combination of ProPhyt + low rate of Captec was not more effective than the solo application of either product.

Technical Abstract: Fungicides were evaluated for control of scab in a mid-ripening experimental nectarine block (‘Redgold’) located at the Clemson University Research Station in Seneca, SC. Chemical formulations were applied with a handgun sprayer (200 gal/A spray volume) on 1 Apr (petal fall), 9 Apr (shuck split) and two subsequent cover sprays on 23 April and 7 May. Treatment regimens included: Captec 4L (two rates), ProPhyt, Captec 4L (low rate) + ProPhyt, Initiate 720 (chlorothalonil), and a non-treated control. Four replications of each treatment were assigned to a randomized complete block design, with each plot consisting of one tree. All cultural practices were in keeping with production methods commonly observed throughout the Southeast. At full maturity, 40 fruit were harvested from each plot for scab assessments (24 Jun). Scab incidence (percent infected fruit) and severity (lesions per fruit) were recorded on the day of harvest. For peach scab, a critical peak in spore production occurs during the period between petal fall and shuck split. Combinations of phosphonate fungicides, such as ProPhyt, with captan-containing products have provided synergistic and/or additive effects for management of diseases in other commodities (e.g. summer rot control in apples). A tank mix of ProPhyt plus Captec (low rate) was compared to solo applications of each and other treatments typically used by growers. All treatments provided a statistically significant decrease in scab incidence and severity as compared with the non-treated control. There were no significant differences between fungicide treatments relative to their abilities to reduce scab as measured by severity. However, distinctions were observed for scab incidence, as a solo application of ProPhyt was less effective at reducing the incidence of scab than all other treatments with the exception of the low rate of Captec. Although numerically the best treatment, the combination of ProPhyt + low rate of Captec was not significantly more effective than the solo application of either product.