Effects of plant conduction systems and organic fertilizer management on disease incidence and severity in ‘Osiana’ and ‘Carola’ roses

Abstract

Conventional pruning is a very common practice for pruning rose cultivars in Brazil. However, few Brazilian producers known any other efficient plant training method for roses, namely “lateral stem bending” or “arching technique”, which involves bending the branches of the rosebush in order to increase the photosynthetic rate of the plant. As well as plant training, the use of fertilizers must also be done carefully in order to obtain high quality roses. Biofertilizers are recommended because of their multiple effects: fertilizer, protein synthesis stimulant, insect repellent, and disease controller. The aim of this study was to assess the plant training system and management of organic fertilizer on the incidence and severity of disease in the ‘Osiana’ and ‘Carola’ roses. The ‘Osiana’ rosebushes received three concentrations (0%, 5%, and 15%) of foliar biofertilizer applied monthly to the leaves together with two plant conduction methods (conventional pruning and lateral stem bending). ‘Carola’ roses were treated with three types of fertilizer (chemical fertilizer on the soil + bokashi on the soil, chemical fertilizer on the soil + foliar FishfertilÒand chemical fertilization on the soil without applying organic fertilizers) every two weeks, together with 2 plant conduction systems (conventional pruning and lateral stem bending). The additional treatments in ‘Carola’ roses were composed of two organic fertilizers (Bokashi and foliar Fishfertil®) and chemical fertilization with lateral pruning. The incidence and severity of disease in these plants during the experiment were assessed over 5 months. For the ‘Osiana’ rose, the incidence and severity of disease were not influenced by fertilizer management or plant training methods. For the ‘Carola’ roses, the different types of fertilizer caused different responses according to the plant training system used, with the biofertilizer Fishfertil® reducing the incidence of powdery mildew when applied to plants with laterally bent stems.