Root frost tolerance, seasonal variation in root growth, and field performance of one-year-old Russian larch seedlings with simulated root freezing damages

Planting healthy seedlings with optimal growth potential is essential for proper growth and survival in forest regeneration. Assessing the seedling quality prior to planting is therefore important. In this Icelandic study, effects of root damage induced with artificial freezing in young Russian larch seedlings were examined using the root growth capacity method (RGC). Frost tolerance of roots varied during the winter, and root growth in undamaged seedlings fluctuated, indicating seasonal variations in growth rhythm. The LT50 value for root frost tolerance was −13.9°C in late January, but already at −10.6°C (LT10) root damages were severe. After one growing season, shoot elongation was significantly lower in seedlings frozen to −9°C, −13.5°C, and −15.5°C by 23%, 54%, and 72%, respectively, compared with undamaged seedlings. Control seedlings and seedlings frozen to −9°C achieved 100% survival after the first growing season. Survival in seedlings frozen to −13.5°C and −15.5°C was 85% and 27%, respectively. After the second growing season, survival decreased in all frost-damaged seedlings. The ongoing mortality demonstrates the long-lasting effects of planting seedlings with damaged root systems, and the fluctuation in root frost tolerance of young Russian larch seedlings during winter emphasises the need for care when seedlings are moved to outdoor storage.publishedVersio

Rhizophusråte (skjeggmugg)

Rhizophus stolonifer er ein svak parasitt som årleg fører til betydelege utfall i julestjerne. Soppen gjer størst skade i stressa eller skadde planter under fuktige og varme forhold. God hygiene og klimastyring er viktige tiltak for å redusere angrepet.Rhizophusråte (skjeggmugg)publishedVersio

Effect of photoperiod and fertilization on shoot and fine root growth in Picea abies seedlings

seedlings were given three different fertilization treatments in the nutrient solution by varying the potassium:nitrogen (K:N) ratios (2.5, 3.0 or 3.9 g g). All fertilization treatments were combined with short-day (SD) treatment or no such treatment (control). Above- and belowground growth responses in the seedlings were analyzed. The SD treatment resulted in significantly reduced shoot height, compared to untreated control, irrespective of K:N ratio. No combination of photoperiod treatment or fertilization treatment affected the root collar diameter. In the current year root fraction with diameter <â0.5 mm, the highest K:N ratio led to significantly increased root length in control plants. In each 0.1 mm root diameter class up to 0.5 mm, the highest K:N ratio significantly stimulated root growth in control plants, while the effect was less evident for SD plants. SD treatment stimulated length growth in some fine root diameter classes. We conclude that SD treatment is a good and sufficient measure to reduce height growth without compromising fine root growth of P. abies seedlings. Fertilization treatment did not significantly improve aboveground growth in SD treated seedlings, and only limited effects on root growth was seen on control plants.Picea abiesâ

Bekjempelse av kjempebjørnekjeks langs vei – relatert til prosjektet E16 Wøyen-Bjørum

Kjempebjørnekjeks er en fremmed art i Norge. Arten er vurdert å utgjøre en høy risiko for annet biologisk mangfold på voksestedet og det er behov for tiltak for å unngå ytterligere spredning. Formålet med denne undersøkelsen var å fremskaffe kunnskap om effektive metoder for bekjempelse av kjempebjørnekjeks i forbindelse med etablering av grøntanlegg ved ny E16 nær Wøyen i Bærum. I tillegg var det et mål å opparbeide kunnskap om hvordan en kan redusere bestandet av kjempebjørnekjeks når jordmasser som legges i ranke under anleggsarbeidet skal tilbakeføres til veganlegget. Problemstillingene er belyst gjennom fire delprosjekt utført i årene 2005-2007. Få frø spirte frem fra de lagrede massene. Individene var imidlertid livskraftige og ville snart kunne ”overta” et større område om ikke tiltak ble igangsatt. Det er derfor viktig med fortsatt fokus på fremspiring av kjempebjørnekjeks etter tilbakeføring av masser som kan være infisert av kjempebjørnekjeksfrø. Plantene er lettest å bekjempe på et tidlig stadium og det vil derfor være viktig å sette inn tiltak allerede i spiringsåret. Rapporten foreligger også som Rapport fra Statens vegvesen, april 2008.publishedVersio

Soil steaming to disinfect barnyardgrass-infested soil masses

Reusing soil can reduce environmental impacts associated with obtaining natural fresh soil during road construction and analogous activities. However, the movement and reuse of soils can spread numerous plant diseases and pests, including propagules of weeds and invasive alien plant species. To avoid the spread of barnyardgrass in reused soil, its seeds must be killed before that soil is spread to new areas. We investigated the possibility of thermal control of barnyardgrass seeds using a prototype of a stationary soil steaming device. One Polish and four Norwegian seed populations were examined for thermal sensitivity. To mimic a natural range in seed moisture content, dried seeds were moistened for 0, 12, 24, or 48 h before steaming. To find effective soil temperatures and whether exposure duration is important, we tested target soil temperatures in the range 60 to 99 C at an exposure duration of 90 s (Experiment 1) and exposure durations of 30, 90, or 180 s with a target temperature of 99 C (Experiment 2). In a third experiment, we tested exposure durations of 90, 180, and 540 s at 99 C (Experiment 3). Obtaining target temperatures was challenging. For target temperatures of 60, 70, 80, and 99 C, the actual temperatures obtained were 59 to 69, 74 to 76, 77 to 83, and 94 to 99 C, respectively. After steaming treatments, seed germination was followed for 28 d in a greenhouse. Maximum soil temperature affected seed germination, but exposure duration did not. Seed premoistening was of influence but varied among temperatures and populations. The relationships between maximum soil temperature and seed germination were described by a common dose–response function. Seed germination was reduced by 50% when the maximum soil temperature reached 62 to 68 C and 90% at 76 to 86 C. For total weed control, 94 C was required in four populations, whereas 79 C was sufficient in one Norwegian population.Soil steaming to disinfect barnyardgrass-infested soil massespublishedVersio

Plantevern i grøntanlegg. Integrert bekjempelse

Boka Plantevern i grøntanlegg – integrert bekjempelsehører med i en serie om integrert plantevern i forskjellige kulturer. Bøkene er ment som en del av pensum til autorisasjonskurset i handtering og bruk av plantevernmidler. Et mål er å hjelpe plantedyrkeren og gartneren med å utføre en integrert bekjempelse av skadegjørere. Integrert plantevern går ut på å kombinere flere forskjellige bekjempelsestiltak, slik at bruken av kjemiske midler blir minst mulig. Samtidig bør resultatet kvalitetsmessig, innenfor en økonomisk forsvarlig ramme, bli best mulig. For plantekulturene som er beskrevet i de andre bøkene i denne serien, er retningslinjer for integrert plantevern utarbeidet i tråd med Landbruksdepartementets Handlingsplan for redusert risiko ved bruk av plante vernmidler (1998–2002). Integrert plantevern i grøntanlegg er fore løpig et nytt begrep i Norge, men etter hvert som det blir innarbeidet, vil det også kunne komme retningslinjer for integrert plantevern i grøntanlegg. Disse vil danne grunnlaget for en merkeordning som for eksempel planteskoler og anleggsgartnere kan bruke i sin markedsføring. Den som skal kunne utføre integrert bekjempelse, må vite hvordan skadegjørerne ser ut, hvordan deres biologi er og hvilke tiltak som er aktuelle. Denne boka viser frem sentrale skadegjørere i grøntanlegg og planteskoler. Ved omtale av kjemiske plantevernmidler har vi valgt ikke å bruke navn på midlene, fordi slike opplysninger forandrer seg over tid.publishedVersio