Effect of cocoa pod husk-based compost and watering frequencies on Phytophthora seedling blight disease suppression and seedling growth of cocoa clones

English. Phytophthora Seedling Blight Disease (PSBD) is a significant threat to global cacao production, causing stem and leaf wilting, defoliation, and seedling death within seven days of infection. The persistence of Phytophthora palmivora Butler in soil as mycelia and spores complicates its management. Composting, particularly with cocoa pod husks, enriches soil and suppresses plant diseases. Cocoa pod husks also present a sustainable substratum for composting, as a substantial amount of it is left unused after bean harvesting. This study investigated the effects of cocoa pod husk-based compost and watering frequencies on PSBD suppression and cocoa seedling performance.  The experiment involved three factors: cocoa hybrid genotypes (PA150 and C85), compost ratios (soil alone, compost alone, 9 kg compost + 81 kg soil, and 18 kg compost + 72 kg soil), and watering frequencies (twice or thrice weekly). Disease incidence, growth, and root architecture parameters were analyzed using GenStat. Results showed significantly higher PSBD incidence in soil alone compared to compost-amended soils (p < 0.05). Growth parameters also varied significantly among treatments (p < 0.05). Cocoa pod husk compost significantly improved cocoa growth and suppressed PSBD, with reduced watering frequency enhancing effectiveness.

Slovenian. Plesen Phytophthora Seedling Blight Disease (PSBD) povzroča venenje stebel in listov, defoliacijo in propad sejank v času sedem dni po okužbi. Obstoj glive Phytophthora palmivora Butler v tleh v obliki micelija in trosov otežuje njeno zatiranje. Uporaba komposta, še posebno tistega iz ostankov plodov kakavovca, bogati tla in zavira to rastlinsko bolezen. Tako predstavljajo ostanki plodov kakavovca znaten vir substrata za kompostiranje, ki je trenutno neizrabljen po izluščenju semen. V raziskavi so bili preučevani vplivi tega komposta in pogostosti namakanja na zatiranje zgoraj omenjen glivične bolezni in rast sejank. Poskus je potekal v Prestea Nkwanta, v Gani in je vseboval tri dejavnike: hibridna genotipa kakavovca (PA150 in C85), delež komposta v substratu (samo prst, samo kompost, 9 kg komposta + 81 kg prsti in 18 kg komposta + 72 kg prsti) in pogostost namakanja (dvakrat ali trikrat na teden). Rezultati so pokazali značilno večji pojav PSBD bolezni v substratu samo iz prsti v primerjavi s tistimi, kjer je bil dodan kompost (p < 0.05). Tudi rastni parametri so bili med obravnavanji značilno različni (p < 0.05). Kompost iz ostankov plodov kakavovca je značilno izboljšal rast kakavovca in zavrl pojav PSBD bolezni, zmanjšal je tudi pogostost namakanja, kar je povečalo učinkovitost pridelave.