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Health condition of common oak acorn (Quercus pubescens) and protection measures in Croatia

Seed production in common oak stands in the last decades is less than in times past and the seed germinability-vitality percentage decreases. The oak acorn is attacked by insects, fungi and rodents. There is growing need to ensure sufficient quantities of acorn for nursery and quantity.Last few years in forest nursery were used several fungicides for seed protection: Cuprablau Z, Dithane, Captane, Panoctine, Radotiram i Vitavax. In this work the health condition and the mycoflora on acorn were investigated. It w as also investigated the effectiveness of different fungicides in pre-sowing treatments. Oak seed were collected in seed stands from five region in forest managments: Vinkovci, Našice, Bjelovar, Karlovac and Zagreb as representatives of common oak in Croatia. The seed were collected from the ground in the middle of october. Seed samples were analysed in phytophatological laboratory of Forest research institute Jastrebarsko. The seed health was analyseed useing macroscopic and microscopic- phytopathological methods. The seed were catagorysed in groups: healthy seed, seed damaged with insects, fungi and rodents. The seed with symptoms of fungi damage were analysed and the fungi were determined. The effectivenessof fungicides were analysed in laboratory (room conditions) and in the field. The seed were treated with fungicides and doses: Cuprablau Z (3g/1kg acorn), Vitavax 200 (2, 5g/1kg acorn), and Dithane S-60 (2g/1kg acorn). In laboratory experiment the seed were put on moist sand and after 6 weeks the seed germination was registered and the fungi on not germinated acorn were analysed. For the fild experiment the acorn were treated with fungicides, stored at 5°C and in spring were sawn in nursery Ivanska. In autmn the number of seedlings were registerd. The results show that the health condition of the seed collected from the forest ground was: healthy seed 15-30%, seed damaged with insects (Curculiuo, Cydia) 45-75%, seed damaged with fungi 25-45% and seed damaged with rodents 3-5%. The phytopathological research show that the most common fungi on acorn were: Ciboria batschiana, Phomopsis quercela, Fusarium spp., Ophiostoma spp., Penicillium spp., Alternaria spp., Trichothecium roseum, and Trichoderma viride were present. The fungicide can protect acorn only partly. In field experiment the percent of germinated acorn-seedlings were when treated with Vitavax 80%, Cuprablau Z 78%, Dithane 75% and controll (no fungicide) 74%. The sedd have important role in sustainable forest managment and the knowledge about biotic factors like mycoflora and insects that influenced seed quality and about protection measures become more important than before.

Quercus pubescens, oak acorn, fungicides, protection measures, mycoflora

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