. Bothalia. Botany. 184 After forty-two hours there was no further change, except in the increased length of the germ tubes and the increased number of spores with two and three septations. At no time was any suggestion of a change of colour observable in the conidia. The ascus stage was not found in culture, but, as stated elsewhere, its connection with the conidial stage has been traced. Inoculation Experiments. Several seedling Avocados in the greenhouse were inoculated with conidia from cultures on oatmeal agar and with pieces of mycelium. In each case a small incision was made in the bark
. Bothalia. Botany. 184 After forty-two hours there was no further change, except in the increased length of the germ tubes and the increased number of spores with two and three septations. At no time was any suggestion of a change of colour observable in the conidia. The ascus stage was not found in culture, but, as stated elsewhere, its connection with the conidial stage has been traced. Inoculation Experiments. Several seedling Avocados in the greenhouse were inoculated with conidia from cultures on oatmeal agar and with pieces of mycelium. In each case a small incision was made in the bark, the infective material inserted, and the branch at the point of inoculation was kept moist for about forty-eight ('onidia after 21 li 25 C The plants which were inoculated with conidia soon showed signs of infection. The tissues around the incision became discoloured and sunken ; in some cases the affected area slowly increased in size tor a few weeks until it was about 1 cm. in diameter, and then its progress was arrested. Two trees became completely girdled, the whole stem was invaded and killed, and after six months typical conidia were produced. The pyenidia and conidia on these artificially infected trees were identical with those found on twigs in the orchard. I'AT.!OL<K3ICAL HiST<)LO<!V. The fungus appears to be a wound parasite, in the cortical tissues of infected twigs t here is a rather coarse brownish mycelium about 3-5 fi thick. The cell walls are discoloured, bat there is no very prominent deposit in any of the cells. At certain spots there are masses of densely woven hyphae in the epidermal and hypodermal cells, which rupture the cuticle,. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Botanical Research Institute (South Africa); Pretoria (South Africa). National Herbarium;
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Keywords: ., bookcentury1900, bookdecade1920, booksubjectbotany, bookyear1921
