Detectie en beheersing van bacterierot veroorzaakt door Pseudomonas cattleyae in Phalaenopsis

Phalaenopsis growers suffer from mayor losses up to 20% due to bacterial spot. This bacterial infection in caused by the Acidovorax avenae subsp. cattleyae. In practice this bacterial disease is also known as Pseudomonas. This bacterium is causing black leaf spots with a yellow border. Pseudomonas cattleyae is very contagious and is promoted by high temperatures en moist conditions. In this project Groen Agro Control laboratory (Delfgauw) has developed a molecular analysis method to detect Pseudomonas cattleyae in different matrices. The influence of the relative humidity on the development of Pseudomonas cattleyae is investigated during this research. The results show that a relative humidity of 90% strongly promotes infection of the bacteria. A relative humidity of 75% shows no extra dispersion of Pseudomonas cattleyae compared to a greenhouse compartment with a continuous relative humidity of 60%. This knowledge offers the opportunity to safe energy in the cultivation of Phalaenopsis. During this research the effects of water treatments on the dispersion of Pseudomonas cattleyae have been investigated. The results show that a treatment with hydrogen peroxide (20 ppm) offers the best reduction of dispersion. This treatment turns out to be better than the control and all other treatments. This research has led to new insights about the dispersal and optimal growing conditions of this bacteria, but leads to new questions. Questions, about other different dosages and the effects of other water treatments, but also about the optimal level to promote plant growth and reduce bacterial infections, have to be investigated in new research.