Anthuriums

The Anthurium industry in Hawaii was devastated by the Anthurium blight (Xanthomonas campestris dieffenbachii) during the 70’s and 80’s. During the 90’s, the Dutch declared that Anthuriums produced in the Netherlands never have that problem. There was truth to that. The problem stems from the difference in production philosophy. 

The Americans need to analyze the media, soil and tissues before they can make solid recommendations for fertilizers. The Dutch, trying to grow everything in recovered silts from the sea beds, assumes that there is nothing in the media and gives all the essential nutrients to the plants everytime they water. 

The nutrient recommendations for crops in Hawaii were basically macronutrients NPK plus trace elements. Calcium, Magnesium and sulfur are assumed to come from ground water and soil but Anthuriums do not grow in soil but in soil-less mixes and City water is usually low in Calcium. With the fast growth of cells induced by the heavy NPK use, there is not enough Calcium to reinforce the cellwalls. Weak cell walls (middle lamella) result in hook leaf and bacterial infections.

The Dutch considers Bacterial Diseases as “Production Systems Defects” and that includes factors like ventilation, light and nutrients. Pampering the plants with sufficient levels of Calcium with every dose of NPK and trace elements, results in balanced healthy tissues tolerant to bacterial infections as shown by their products.

The Hawaiians are now incorporating Dolomite (Calcium and Magnesium Carbonate) in the media mix to prevent bacterial problems. With the success of Silica application research against bacterial and fungal infection in Aglaonema, Silica is now being tried on Hawaiian Anthuriums.

The Anthurium Rot of the 80’s that devastated several big Anthurium collections in the Philippines were incorrectly diagnosed as Bacterial Blight. They actually succumbed to Fusarium when growers refused to use Benlate because of the Benlate scare of 1972 (Dioxin contamination in DF or field grade Benlate). Benomyl and Carbendazim are the most potent chemicals available for Fusarium. Fusarium causes rotting of the roots that extend into the stem, causing flagging or softening of the stem and eventual death of the infected plants. Nitrogen fertilization and waterlogging catalyze the process.   

Bacteria: Xanthomonas, Pseudomonas and Erwinia can stay on Anthurium collection without causing rots and plants may be asymptomatic for years. Antibiotics applications do not help either and will cause growth abberations..

The most recent Anthurium research output of the Dutch company Anthura is the recommendation to cutting of the first 1/3 tip of the leaf while it is unfolding to optimize photosynthesis and thus, the flower size.