Studies on the chemical control of Phytophthora palmivora (Butl.) Butl. on Theobroma cacao L. in Nigeria

Abstract

S U M M A R YI n laboratory trials, phenyl mercury nitrate at 0-02 p.p.m. and fentin acetate at 0.2 p.p.m. severely retarded growth of four isolates of Phytophthorapalmivora on cassava agar. These two chemicals, with captan, maneb and a dithiocarbamate-copper chelate, were also highly toxic to encysted zoospores of a 'rubber' group isolate of P. palmivora.Deposits of captan on pods were readily removed by artificial rain, but some improvement in tenacity was obtained by the addition of a sticker. I n other laboratory trials, the deposit from low-volume sprays of cuprous oxide dried more quickly on pods than that from high-volume sprays but showed no advantage in subsequent resistance to weathering.I n a field trial in 1961, seven fungicide treatments were applied three-weekly and compared with an unsprayed control. T h e lowest percentage black-pod infection followed treatment with fentin acetate : Bordeaux mixture and carbide Bordeaux both gave good control. The captan treatments were completely ineffective. More black pods were harvested from close-spaced trees than from those wide-spaced.Weekly applications of 0-15 yo fentin acetate to seedlings induced no significant damage. I n a field trial made in 1962 very heavy rainfall provided a severe test of the fungicides, the most effective being Bordeaux mixture and carbide Bordeaux mixture applied three-weekly, carbide Bordeaux mixture applied four-weekly and fentin acetate applied two-weekly. Captan with added sticker was again no better than the control. There was no marked effect of spacing.Comparisons of Bordeaux and carbide Bordeaux mixtures made at two other sites in 1962 showed no difference in disease control. It is suggested that carbide Bordeaux mixture could be replaced by the cheaper preparation made with lime.

Efecto de preparados minerales sobre el crecimiento y desarrollo in vitro de Moniliophthora roreri (Cif. & Par.) Evans

“…Uno de los preparados minerales más conocidos es el caldo bordelés, que se ha empleado con éxito para controlar Phytophthora palmivora en el cacao (Hislop, 1963; …”

“…One of the best known minerals is Bordeaux mixture, which has been used successfully to control Phytophthora palmivora in cocoa (Hislop, 1963;Adejumo, 2005) also have shown good results on different pathogens with other products such as sodium bicarbonate (Dik et al, 2003;Dessalegn et al, 2013) and calcium polysulfide (Holb and Schnabel, 2008;Jamar et al, 2010); the latter was tested to control of M. roreri, finding that in vitro reduced the number of conidia by up to 74% and Adejumo, 2005), además se han obtenido buenos resultados sobre diferentes fitopatógenos con otros productos, como el bicarbonato de sodio (Dik et al, 2003;Dessalegn et al, 2013) y el polisulfuro de calcio (Holb y Schnabel, 2008;Jamar et al, 2010); este último fue probado para el control de M. roreri, encontrándose que in vitro redujo el número de conidias hasta 74% y en campo logró bajar la incidencia a 0.53%, frente a 21% en el tratamiento con manejo cultural y 69.6% en el testigo sin manejo (Ramírez et al, 2011a).…”

Application of chemical and biological agents for the management of frosty pod rot (Moniliophthora roreri) in Costa Rican cocoa (Theobroma cacao)

“…by reducing the number of tank loads per hectare. Although low‐volume spraying with motorised mistblowers (MMs) was specifically developed for cocoa (Hislop, 1963; Clayphon, 1971), much pesticide application takes place using low‐cost, manual (hydraulic) knapsack sprayers.…”

Effect of Actidione, Griseofulvin and Triphenyltin Acetate on the Kinetics of Fungal Growth

“…Actidione inhibits protein synthesis in eucaryotic organisms but the mode of action of TPTA and griseofulvin is unknown although it has been suggested that the latter interferes with chitin biosynthesis (Brian, 1949). Triphenyltin compounds have recently been used to control fungal pathogens of plants (Hislop, 1963 ;Stallknecht & Calpouzos, 1968).…”