Abstract
Phoma blight of conifer seedlings is poorly studied. The main causal agent in Belarus differs in DNA sequence from other described Phoma species, and has not been fully taxonomically described, and therefore has been temporarily designated Phoma sp. 1. The basic morphological and growth culture characteristics of Phoma sp. 1 have recently been published. This report provides additional data about the influence of macro- and micro-elements on the growth of Phoma sp. 1 in vitro to complement the description of growth culture and morphological features. It was found that addition of tricalcium phosphate and potassium chloride to the media at concentrations of 1 g/l and 2 g/l slows the mycelial growth by an average of 30%. The micro-elements copper sulphate (at 50 mg/l and 100 mg/l) and zinc sulphate (at 100 mg/l) decreased growth by 50%, 63%, and 32%, respectively. Urea completely inhibited Ph. sp.1 growth at 0.5 g/l. Summarising previously published information, Phoma sp. 1 is a mesophilic acidophile, capable of forming chlamydospores in culture. Pycnidia form deep in the media only after prolonged low-temperature storage. The optimal pH for growth is 4.3–4.9. Constant medium aeration favours the formation of typical mycelium, proportional growth and stable biomass accumulation.