Juha Kaitera, Heikki Nuorteva. (2010). Effects of Melampyrum extracts on the growth of axenic cultures of Cronartium flaccidum and Peridermium pini. Silva Fennica vol. 44 no. 2 article id 149. https://doi.org/10.14214/sf.149

Keywords: Scots pine; alternate host; anti-fungal phytochemicals; fungal growth regulation; pine stem rust

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For 3–6 months, mycelial colonies cultured from 5 isolates of each of two pine stem rusts (Cronartium flaccidum and Peridermium pini) were grown on nutrient-rich agar supplemented with Melampyrum extracts. Non-autoclaved extracts of M. pratense significantly reduced the growth of P. pini. The growth of C. flaccidum isolates was slightly stimulated after the second month of incubation but after that was inhibited during incubation months 4–6. We observed considerable variation in colony growth, a significant component of which was explained by incubation time, isolate, growth medium and their interaction. Rust species (C. flaccidum or P. pini) was not an important factor in growth variation. While sterilized extracts of M. pratense, M. sylvaticum and M. nemorosum did not significantly affect growth, colonies of C. flaccidum were slightly stimulated, whereas colonies of P. pini were slightly inhibited. Generally, isolates of P. pini grew better and showed a slower rate of degeneration than C. flaccidum on all media.

Kaitera, Finnish Forest Research Institute, Northern Finland Regional Unit, FI-91500 Muhos, Finland E-mail: juha.kaitera@metla.fi
Nuorteva, Finnish Forest Research Institute, Southern Finland Regional Unit, FI-01301 Vantaa, Finland E-mail: hn@nn.fi

Category : Research note

article id 702, category Research note

Timo Kurkela, Heikki Nuorteva. (1998). Short-needle disease of Scots pine: an abnormal needle length distribution. Silva Fennica vol. 32 no. 1 article id 702. https://doi.org/10.14214/sf.702

Keywords: Pinus sylvestris; Scots pine; needle length; insect feeding; tissue deformation

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Short-needle syndrome occurs commonly in southern Finland. The disease is characterized by abnormal length distribution of the needles in shoots. In most cases, affected shoots have needles of normal length as well as very short needles. The short needles are those injured during the needle elongation period; the tissues formed abnormal sclerenchymatic structures and wound periderm. One possible cause could be hemipterous insects feeding on growing needles. Salivary sheaths of such insects were often present in both deformed needle bases and undeformed mature tissues.

Kurkela, Finnish Forest Research Institute, P.O. Box 18, FIN-01301 Vantaa, Finland E-mail: timo.kurkela@metla.fi
Nuorteva, Finnish Forest Research Institute, P.O. Box 18, FIN-01301 Vantaa, Finland E-mail: hn@nn.fi

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