Fungal plant pathogens causing cereal diseases in Finland have been studied by a literature survey, and a field survey of cereal leaf spot diseases conducted in 2009. Fifty-seven cereal fungal diseases have been identified in Finland. The first available references on different cereal fungal pathogens were published in 1868 and the most recent reports are on the emergence of Ramularia collo-cygni and Fusarium langsethiae in 2001. The incidence of cereal leaf spot diseases has increased during the last 40 years. Based on the field survey done in 2009 in Finland, Pyrenophora teres was present in 86%, Cochliobolus sativus in 90% and Rhynchosporium secalis in 52% of the investigated barley fields. Mycosphaerella graminicola was identified for the first time in Finnish spring wheat fields, being present in 6% of the studied fields. Stagonospora nodorum was present in 98% and Pyrenophora tritici-repentis in 94% of spring wheat fields. Oat fields had the fewest fungal diseases. Pyrenophora chaetomioides was present in 63% and Cochliobolus sativus in 25% of the oat fields studied.

Tap‐rooted rapeseed is generally considered sensitive to soil compaction. We examined 473 Finnish rapeseed fields sown in 2007 to 2009 to both spring turnip rape Brassica rapa L. (dominant crop) and oilseed rape Brassica napus L. Roots were rated late in the growing season according to penetration capacity. Roots in each field were rated from G1 (no problems with root penetration) to G5 (failure to penetrate deeper soil layers). There were significant effects of year, crop species, soil type, special soil properties and soil cultivation methods on frequency of G1 and G4+5 roots. Restricted root penetration was a common phenomenon. Typically, fields had <30% G3 and G4+5 roots, however, some fields had >70% G4+5 roots and were cases for serious concern. Yield loss was linearly related to the incidence of G4+5 plants in 2007, but there was no relationship with the other years. Oilseed rape had a greater proportion of G4+5 roots than turnip rape and twice the proportion of G4+5 roots occurred in direct‐drilled fields than in reduced or fully tilled fields. Rapeseed yield decline may at least partly be related to poor root penetration and it is a useful indicator crop to demonstrate the degree of soil compaction and should be cultivated in fields where sufficient root penetration is possible.

A disease survey in Finnish oilseed Brassica (OSR) fields in 2007-09 revealed the widespread occurrence and several fold increase of necrotic stem base lesions and severely injured blackened roots in comparison to a corresponding survey carried out in 1984-89. Rhizoctonia solani was the predominant fungi detected in the isolations and was followed by several species of Fusarium and Thielaviopsis basicola. In 60% of the samples all three species were detected together. Only the R. solani AG 2-1 strains isolated from OSR and other cruciferous hosts caused damping off or stem base symptoms on turnip rape in a greenhouse experiment. Therefore R. solani AG 2-1 was considered the main pathogen associated with the observed symptoms in OSR crops. Cultural practices changed significantly between the 1980s and 2000s. In the 2007-09 survey there was an increase in the cultivation of oilseed rape instead of turnip rape, increase in the use of no soil or reduced soil tillage and of chemical control of weeds, but a reduction in macronutrient fertilization, especially P and K, when compared to the 1980s survey. The risk for high incidence of stem base lesions and blackened roots was affected by different cultural practices. No tillage and maintaining sufficient soil pH and NPK fertilisation decreased the risk for both types of R. solani induced symptoms. Late sowing date increased the risk for high incidence of stem base lesions, while application of fungicides against Sclerotinia reduced it. The incidence of R. solani damages in many fields was very high in spite of relatively long crop rotations and therefore the average effect of crop rotation in the disease was insignificant. Current turnip rape cultivars are vulnerable to root rot while oilseed rape is vulnerable to stem base symptoms. The higher incidence of R. solani induced diseases could be associated with the decline in productivity of OSR crops in Finland. This study showed that cultural practices such as reduced or no soil tillage, adequate levels of pH and of NPK fertilization could reduce the severity of the symptoms in OSR fields.

A survey of weeds in spring-sown oilseed crops (Brassica rapa ssp. oleifera and Brassica napus ssp. oleifera) was conducted in southern and central Finland during 2007Finland during -2009, representing the first such extensive investigation in the country. The occurrence of the most abundant weed species in oilseeds was surveyed in 429 fields. In the fields with moderate or high weed infestation, 1-6 harmful weed species were recorded by visual observation according to their biomass production. About 40 weed species were recorded, the most predominant being Chenopodium album, Galeopsis spp., Galium spurium, Sonchus arvensis and Tripleurospermum inodorum. Elymus repens was the only major grass weed. Chemical weed control of broad-leaved weeds had been practised in 53% of the fields, resulting in relatively good control. In addition, both selective graminicides and glyphosate were used to control E. repens. Mechanical weed control was not practised in any field. The crop yield level was about 300 kg ha -1 higher in the fields with low weed infestation compared with in the highly infested fields. New promising options to replace the banned herbicide trifluralin are available. Thus, the most harmful weeds, such as C. album, which interferes with the production of high-quality oil for human consumption, can still be effectively controlled.

Tiivistelmä Ilmaston muutoksella on monia vaikutuksia kasvintuhoojien menestymiseen ja vahingollisuuteen Suomessa. Viljelyn ja riskien muuttuessa myös torjunta muuttuu monella tavalla. Kasvinsuojeluriskien kasvu on alkanut jo ja odotettavissa on ”kolme riskiaaltoa”. Ensimmäisenä voivat näkyä lämpötilan ja kosteuden muutosten suorat vaikutukset. Toinen ”riskiaalto” liittyy syyskylvöisten kasvien ja ympärivuotisen viljelyn yleistymiseen. Monet tuhoojat voivat jatkaa aktiivivaiheen kehitystä ympärivuotisesti. Populaatiokoot moninkertaistuvat ja vastaavasti tuhoojien aiheuttamat haittavaikutukset lisääntyvät. Kemiallisen torjunnan painopiste alkaa siirtyä keväästä ja kesästä syksyyn. Kolmas ”riskiaalto” liittyy täysin uusien viljelykasvien tuloon ja niitä seuraavien uusien kasvintuhoojien kotiutumiseen Suomeen. Puutarhatuotannossa taimituonti nopeuttaa riskien kasvua olennaisesti jo nyt. Ilmaston muutoksesta hyötyviä tuholaisia ovat mm. kirvat, punkit ja ankeroiset, jotka lisääntyvät niin pitkään kuin kasvustoissa on niille sopivaa ravintoa. Lämpösumman kasvu avittaa myös monen tulokaslajin juurtumista Suomeen. Syksyn muutoksesta hyötyviä tuholaisia ovat esim. etanat ja monet kärpäset. Kirvojen runsastumiseen liittyy merkittävä virustautien levintäriski. Lämpö ja kosteusjaksojen lisääntyminen suosivat useimpia kasvitauteja ja pitenevä kasvukausi altistaa kasvit pidempään taudinaiheuttajille. Eniten kasvitautien lajikirjoa avomaalla tulee muuttamaan siirtyminen kevätmuotoisista viljoista ja öljykasveista syysmuotoihin. Muuttuva ilmasto tulee suosimaan erityisesti viljojen ruoste- ja härmätauteja, jotka nykyisin ovat meillä melko satunnaisia. Syysohran viljely mullistaa ohranhärmän epidemioiden dynamiikan täysin. Lämpenevät säät ja lisääntyvä kosteus hyödyttävät monia bakteeritauteja, fytoplasmoja, viruksia ja niiden vektoreita, joista voi koitua lisääntyvää riesaa niin viljoille, perunalle kuin puutarhakasveille. Rikkakasveista kilpailukykyään nopeimmin lisäävät rikkaheinät. Syyskylvöisten kasvien viljelyn laajentuminen nostaa syysitoisten 1-vuotisten rikkakasvien merkitystä. Tulevaisuudessa kasvinsuojeluriskien hillintä perustuu entistäkin enemmän kotimaisen ja terveen lisäysmateriaalin käyttöön joten terveen lisäysmateriaalin tuotantokapasiteetti pitää säilyttää. Samoin taudinkestävien lajikkeiden jalostus pitää turvata riittävällä resursoinnilla. Riskimuutosten seurantaan tarvitaan systemaattinen tarkkailujärjestelmä ja tehokas tiedonvälitys. Torjuntatarpeen ajoituksen muuttuessa kasvinsuojeluaineiden ruiskutus siirtyy syksyyn ja kasvinsuojelusta aiheutuvat ympäristöriskit lisääntyvät. Panostus biologiseen torjuntaan ja ekosysteemipalvelujen tuntemiseen on välttämätöntä, jos halutaan välttää kasvinsuojelusta tai sen epäonnistumisesta aiheutuvat riskit. Viljelyjärjestelmien kehittämisessä ja maankäytössä on painopiste siirrettävä kesäkaudesta talveen, koska talvikauden biologiset prosessit muuttuvat eniten. Onnistunut sopeutuminen talvikauden muutoksiin ratkaisee riskienhallinnan kokonaisuuden.