Germination of sclerotia of Botrytis tulipae, the cause of tulip fire

Sclerotia of Botrytis tulipae (Lib) Lind. buried in field soil germinated mainly in winter and early spring to produce conidiophores and conidia and then decayed. Except when buried very late in the year sclerotia germinated and decayed in the season following burial. In the laboratory, sclerotia from pure culture germinated in two ways. On sterile water-agar they formed colourless mycelium but no conidiophores; the rate of germination was greatest at 25 d?C. On unsterile filter paper and on soil they produced mainly conidiophores and conidia; the rate of germination was greatest at 5 d?C and was enhanced by previous cold treatment. It was unaffected by soil-moisture or pH. Primary infections of tulips arose from sclerotia placed in the soil but only when they were close to the shoot tip or developing stem. It is suggested that, because of their limited survival, soil-borne sclerotia are of importance only when tulips are planted in annual succession.     

Systematic bark morphology of some tropical trees

YUNUS, M., YUNUS, D & IQBAL, M., 1990. Systematic bark morphology of some tropical trees. Bark of 103 tropical trees of India has been examined from a systematic viewpoint and macroscopic features for use in field identification are considered. They are broadly categorized on the basis of diverse surface patterns and configurations as: deep fissured, shallow fissured, dippled, and entire. Identification of species is facilitated by the nature of the periderm and expansion tissue. The significance of bark anatomy in relation to systematics is discussed.     

Anatomy of the vascular cambium of Acacia nilotica (L.) Del. var. telia Troup (Mimosaceae) in relation to age and season

the majority of fusiform initials are multinucleate, a few having as many as eight nuclei. Their length increases down the stem from the apex, attaining a maximum in the old trunk and declining slightly near the base. The width of the initials exhibits similar variation. In the main trunk, fusiform initials, relatively short at the time of cambial reactivation (April), elongate steadily until July. There is a sharp decline in August/September, the cell length recovering during the winter. Seasonal variation in cell width is inconsistent. Ray cell initials, on the other hand, do not vary much in size. They divide more frequently in the older stem, adding to the size of rays. In young shoots, short and uni- to biseriate rays are most abundant, whereas tall and multiseriate rays dominate the cambial surface in the trunk region throughout the year, with their minimum population in the early phase of cambial activity and the maximum during peak activity. The overall proportion of fusiform initials in the cambial cylinder initially increases with age, from young shoots towards the base, and later becomes more or less constant in the trunk region. Here it remains noticeably high during the active growth period and relatively low for the rest of the year.     

Anatomy of the vascular cambium of Acacia nilotica (L.) Del. var. telia Troup (Mimosaceae) in relation to age and season

the majority of fusiform initials are multinucleate, a few having as many as eight nuclei. Their length increases down the stem from the apex, attaining a maximum in the old trunk and declining slightly near the base. The width of the initials exhibits similar variation. In the main trunk, fusiform initials, relatively short at the time of cambial reactivation (April), elongate steadily until July. There is a sharp decline in August/September, the cell length recovering during the winter. Seasonal variation in cell width is inconsistent. Ray cell initials, on the other hand, do not vary much in size. They divide more frequently in the older stem, adding to the size of rays. In young shoots, short and uni- to biseriate rays are most abundant, whereas tall and multiseriate rays dominate the cambial surface in the trunk region throughout the year, with their minimum population in the early phase of cambial activity and the maximum during peak activity. The overall proportion of fusiform initials in the cambial cylinder initially increases with age, from young shoots towards the base, and later becomes more or less constant in the trunk region. Here it remains noticeably high during the active growth period and relatively low for the rest of the year.     

Testing the viability of fungal sclerotia

Simple methods for producing, handling and testing the viability of sclerotia were used on five fungi, three of which produced sclerotia freely in sand-maizemeal cultures; the other two did not, and were grown on agar. After air drying, which did not affect viability, sclerotia were buried in the field in bags of nylon fabric. After recovery from soil they were surface-sterilized with calcium hypochlorite and plated on a medium containing chloramphenicol and streptomycin sulphate. Some fungi, particularly those having basidiomycete affinities, are sensitive to high concentrations of chloramphenicol.