Further studies on cypress canker disease in east Africa caused by Monochaetia unicornis (Cookie & Ellis) sacc.

Abstract

The relationship that exists between height and diameter growth increments of Cupressus lusitanica was found to be stochastic, with an overall correlation coefficient of 0.979 for the entire plantation population. Maxima of up to 8.91 m in height and 12.50 cm in diameter were achieved after a growth period of about 5 years. Incidence of canker infection appeared higher in faster growing progeny classes than in the slower growing ones when individual trees were considered but this trend was not strongly reflected when the results were pooled. The highest recorded canker attack in a single progeny class was about 60% while the lowest was 8%. Peak infection was recorded at a plantation age of about 3 years after which the infection started to decline. Some “Plus Trees” were found to be unacceptable for inclusion in the future genetic improvement programme and there is a case for a second selection pressure on seed orchards already established from siblings of these “Plus Trees”.