Phytotoxicity of Copper-Based Bactericides to Peach and Nectarine

Abstract

Organometallic copper, consisting of a mixture of copper abietate, copper linoleate, and copper oleate (CuALO), is important for postbloom management of bacterial spot in New Jersey peach and nectarine orchards. Rotation of CuALO with oxytetracycline reduces cost and helps prevent (or delay) resistant organisms. However, because copper is also phytotoxic, higher rates and inorganic coppers have not been utilized. A study was conducted on ‘Encore’ peach and ‘Redgold’ nectarine to determine the quantitative relationship between copper concentration (metallic equivalent) and phytotoxicity. Different rates of CuALO and copper hydroxide (CuOH) were applied seven times postbloom. Foliar injury and defoliation increased with number of applications and copper concentration. Maximum ‘Encore’ defoliation was 10 to 17%, while ‘Redgold’ sustained 30 to 35% leaf loss. CuOH caused similar or less leaf injury and defoliation than CuALO. No injury was observed on fruit, even at three times the labeled metallic copper rate of CuALO. Fruit size and soluble solids were not influenced by copper. Estimates of foliar density and tree volume indicated that sufficient photosynthetic capacity existed to allow acceptable leaf damage and loss from copper applications. These results showed that inorganic coppers may be viable alternatives to organometallic copper for postbloom bacterial spot control; nectarine may be more sensitive to copper injury than peach; and higher rates of metallic copper, above the current commercial rate, can be applied to peach. In the latter case, greater amounts of copper may provide longer residual activity and improved bacterial spot control on highly susceptible cultivars.

Biological control of bacterial plant diseases with Lactobacillus plantarum strains selected for their broad‐spectrum activity

“…Because of the restrictions on the use of commercial products, LAB strains could be a promising alternative tool to be included in disease management strategies. In particular, phytotoxicity and pathogen resistance selections, in terms of copper compounds and antibiotics used for Psa, Xap and Xf control, have been reported (Colombi et al, ; Lalancette & McFarland, ; Roberts, Jones, Chandler, & Stall, ). However, with some plant, defence elicitors such as ASM (Reglinski et al, ) and commercial microbial biopesticides based on Bacillus spp.…”

“…Managing these diseases mainly relies on preventive applications of bactericides containing copper compounds or antibiotics (Cameron & Sarojini, ; Lamichhane, ). However, the selection of resistant pathogen populations and phytotoxicity are the main drawbacks to this practice (Lalancette & McFarland, ; McManus, Stockwell, Sundin, & Jones, ). Overall, reliance on conventional pesticides needs to be reduced and an integrated pest management (IPM) framework implemented (Lamichhane et al, ).…”

Epibrassinolide induces changes in indole-3-acetic acid, abscisic acid and polyamine concentrations and enhances antioxidant potential of radish seedlings under copper stress

“…Cu is an indispensable component of diverse plant metabolic reactions, such that its role as a structural element in regulatory proteins and participation in photosynthetic electron transport, mitochondrial respiration, oxidative stress response, cell wall metabolism and hormone signaling are well established (Raven et al 1999). Plants meet their Cu requirements from the natural soils, but toxic levels of Cu could occur in soils and water bodies as a result of its anthropogenic release from mining, smelting, manufacturing and agriculture industries (Lalancette and McFarland 2007). Excess of Cu metal catalyzes the formation of reactive oxygen species ROS), such as OH • ions from the non‐enzymatic reaction between superoxide (O 2 − ) and hydrogen peroxide (H 2 O 2 ) (Halliwell et al 1987, Luna et al 1994).…”

Enhancing effects of 24-epibrassinolide and Putrescine on the antioxidant capacity and free radical scavenging activity of Raphanus sativus seedlings under Cu ion stress

“…It is a structural element of key regulatory proteins and participates in photosynthetic electron transport, mitochondrial respiration, oxidative stress response, cell wall metabolism and hormone signaling (Murphy and Taiz 1997;Raven et al 1999). Copper requirement of plants are usually met from the natural soils; however, it could occur in soils and water bodies in excess due to its anthropogenic release from smelting, mining, manufacturing and agriculture industries (Lalancette and McFarland 2007). Cu present in excess has been known to cause decreased root biomass and altered plant metabolism (Sheldon and Menzies 2005;Chatterjee et al 2006).…”