Climate change represents an unprecedented challenge to the world?s biosphere and to the global community. It also represents a unique challenge for plant health. Human activities and increased market globalization, coupled with rising temperatures, has led to a situation that is favourable to pest movement and establishment. This scientific review assesses the potential effects of climate change on plant pests and consequently on plant health. The evidence assessed strongly indicates that climate change has already expanded some pests? host range and geographical distribution, and may further increase the risk of pest introduction to new areas. This calls for international cooperation and development of harmonized plant protection strategies to help countries successfully adapt their pest risk management measures to climate change.

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Scientific review of the impact of climate change on plant pests: a global challenge to prevent and mitigate plant pest risks in agriculture, forestry and ecosystems.

Kevatviljapeltojen rikkakasvillisuutta kartoitettiin Etela- ja Keski-Suomessa 16 alueella Nivala-Vierema-Kitee -akselin etelapuolella vuosina 2007-2009. Tutkimuksessa oli mukana yhteensa 595 peltoa 283 maatilalta. Pelloista 523 oli tavanomaisesti viljeltyja ja 72 luonnonmukaisesti viljeltyja. Rikkakasvien tiheys laskettiin kymmenelta ja kuivapaino maaritettiin neljalta 0,1 m2 (40 x 25 cm) havaintoruudulta. Aineisto kerattiin heinakuun puolivalin ja elokuun alkupuolen valisena aikana. Rikkakasvillisuuden pitkaaikaiseen seurantaan liittyvat vastaavat kartoitukset on tehty 1960- ja 1980-luvun alussa seka viimeksi 1997-1999. Valtaosa tutkituista pelloista oli samoja kuin 90-luvun kartoituksessa.Kevatviljapelloilta loydettiin yhteensa 148 rikkakasvilajia, joista 128 oli levealehtisia ja 20 heinamaisia rikkakasveja. Tavanomaisesti viljeltyjen torjunta-aineilla ruiskutettujen peltojen yleisimmat rikkakasvit olivat pelto-orvokki (83 % tutkituista pelloista), pihatahtimo (65 %), pillikkeet (59 %), peltomatara (59 %), linnunkaali (57 %) ja kiertotatar (53 %) seka heinamaisista lajeista juolavehna (50 %) ja kylanurmikka (33 %). Luonnonmukaisesti viljeltyjen peltojen yleisimmat lajit olivat puolestaan jauhosavikka (96 %), pihatahtimo (94 %), pelto-orvokki (94 %), juolavehna (89 %), peltohatikka (89 %) ja pillikkeet (88 %). Luonnonmukaisesti viljellyilla pelloilla kasvoi keskimaarin 21 rikkakasvilajia ja tavanomaisesti viljellyilla ruiskutetuilla pelloilla 12 lajia. Ruiskutetuilla tavanomaisen viljelyn pelloilla kasvoi rikkakasveja keskimaarin 160 kpl/m2 (mediaani: 112) ja luonnonmukaisesti viljellyilla pelloilla 519 kpl/m2 (mediaani: 468). Rikkakasvien tuottama biomassa oli vastaavasti 167 kg/ha (mediaani: 82) ja 775 kg/ha (mediaani: 563). Rikkakasvien osuus kevatviljapeltojen kasvimassasta (vilja + rikkakasvit) oli ruiskutetuilla tavanomaisen viljelyn pelloilla keskimaarin 3 % ja luomupelloilla 21 %. Juolavehnan osuus rikkakasvien tuottamasta kokonaismassasta oli kummassakin viljelymuodossa suurin, tavanomaisen viljelyn pelloilla 28 % ja luomupelloilla 31 %. Rikkakasvilajiston kartoituksen yhteydessa otettiin myos peltomaan pinnasta (0-5 cm) maanayte rikkasiemenpankin maarittamista varten. Maanaytteista seulottiin ja tunnistettiin yhteensa 27 rikkakasvilajia. Viiden sentin maakerros sisalsi keskimaarin 1684 siementa neliometrilla runsaimpana lajina oli jauhosavikka. Rikkakasvien kasvutiheys ja kasvimassa olivat tavanomaisesti viljellyilla pelloilla suunnilleen samalla tasolla kuin 1990-luvun lopussa, jolloin edellinen kartoitus tehtiin. Yleisimmat rikkakasvit ovat tavanomaisessa viljelyssa paaosin samoja lajeja kuin 1990-luvulla, mutta esim. peltomatara ja peltoemakki ovat yleistyneet selvasti. Juolavehna on edelleen tavanomaisen viljelyn haitallisin ja eniten biomassaa tuottava laji, joskin sen osuus rikkakasvien kokonaismassasta on pudonnut alle 30 %:iin oltuaan noin 50 % kymmenen vuotta sitten. Glyfosaatin kaytto on kymmenen vuoden kuluessa yli kaksinkertaistunut, mika selittanee havaittua juolavehnatilannetta. Levealehtisten rikkakasvien torjuntaan hyvaksyttyjen valmisteiden valikoimaan on viime vuosina saatu uusia vaihtoehtoja, joilla parjataan nykyisen rikkakasvilajiston kanssa, mukaan lukien esimerkiksi peltomatara. Nykyinen keskimaarainen torjuntatulos takaa kevatviljojen riittavan ja laadukkaan sadontuoton. Luonnonmukaisesti viljellyilla pelloilla yleisimpia rikkakasvilajeja esiintyi lahes joka pellolla. Kymmenen vuoden aikana merkittavimmin yleistyneita lajeja olivat peltoemakki (+17 %), ukontatar (+ 15 %) ja peltolemmikki (+12 %). Rikkakasvien kasvutiheys ja kasvimassa oli huomattavan korkea ja haittaa merkittavasti sadontuottoa. Keskimaarainen rikkakasvimassa oli noin 100 kg/ha suurempi kuin kymmenen vuotta sitten, ja juolavehnan osuus on lisaantynyt. Jauhosavikka, peltohatikka, peltovalvatti ja pillikkeet olivat seuraavaksi tarkeimpia biomassan tuottajia. Yhdellakaan pellolla ei torjuttu rikkakasveja mekaanisesti kasvavasta viljasta, mika voisi olla osittainen ratkaisu rikkakasvien nykyista parempaan hallintaan.

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Composition of weed flora in spring cereals in Finland - a fourth survey

Direct control of perennial weeds between crops – implications for organic farming

Tramline establishment in controlled traffic farming based on operational machinery cost

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Incompatibility between fertility building measures and the management of perennial weeds in organic cropping systems

Torresen KS, Fykse H & Rafoss T (2010). Autumn growth of Elytrigia repens, Cirsium arvense and Sonchus arvensis at high latitudes in an outdoor pot experiment. Weed Research50, 353–363.



Summary

Autumn growth of weeds (i) provides an opportunity for mechanical and chemical control in autumn and (ii) can be important for weed survival and infestation in the following spring. Growth characteristics of Elytrigia repens, Cirsium arvense and Sonchus arvensis in autumn were studied in 2004 and 2005, on plants of different origins and developmental stages (planted at various times from May to August). The plants were grown outdoors in large pots and were assessed during September and October each year. The study showed that (i) all species grew in autumn, but growth ceased and the species withered at different times; S. arvensis first, followed by C. arvense and then E. repens and (ii) less developed (i.e. younger) plants grew later in the autumn. This was demonstrated by leaf area development and biomass distribution during autumn. Older plants had a greater total biomass with relatively more rhizomes or creeping roots than younger plants. In young plants of C. arvense and S. arvensis, the biomass of creeping roots increased during autumn. The total biomass, however, changed little during autumn. These growth patterns indicate that E. repens will be the easiest, S. arvensis the most difficult and C. arvense in between, regarding control of these species in autumn.

Autumn growth of Elytrigia repens, Cirsium arvense and Sonchus arvensis at high latitudes in an outdoor pot experiment

In autumn, agricultural perennial weeds prepare for winter and can store reserves into creeping roots or rhizomes. Little is known about influence of climate change in this period. We tested the effect of simulated climate change in autumn on three widespread and noxious perennial weeds, Elymus repens (L.) Gould, Cirsium arvense (L.) Scop. and Sonchus arvensis L. We divided and combined simulated climate change components into elevated CO2 concentration (525 ppm), elevated temperatures (+2-2.5°C), treatments in open-top chambers. In addition, a control in the open-top chamber without any increase in CO2 and temperature, and a field control outside the chambers were included. Two geographically different origins and three pre-growth periods prior to the exposure to climate change factors were included for each species. All species increased leaf area under elevated temperature, close to doubling in E. repens and quadrupling in the dicot species. E. repens kept leaves green later in autumn. C. arvense did not benefit in below-ground growth from more leaf area or leaf dry mass. S. arvensis had low levels of leaf area throughout the experiment and withered earlier than the two other species. Below-ground plant parts of S. arvensis were significantly increased by elevated temperature. Except for root:shoot ratio of C. arvense, the effects of pure elevated CO2 were not significant for any variables compared to the open-top chamber control. There was an additive, but no synergistic, effect of enhanced temperature and CO2 . The length of pre-growth period was highly important for autumn plant growth, while origin had minor effect. We conclude that the small transfer of enhanced above-ground growth into below-ground growth under climate change in autumn does not favour creeping perennial plants per se, but more leaf area may offer more plant biomass to be tackled by chemical or physical weed control.

https://onlinelibrary.wiley.com/doi/epdf/10.1111/gcb.14976

Autumn growth of three perennial weeds at high latitude benefits from climate change.

The main models within the MILDRI modelling network for studying plant protection, PVNOR, a dynamic model which simulates the development of weeds and diseases in cereals, and FARMNOR, an economic ...

Production systems and plant protection requirements in cereals: a model analysis of long-term effects

The early growth of spring barley (Hordeum ulgare L.), Brassica rapa L. ssp. oleifera (DC.) Metzger, Stellaria media (L.) Vill. and Viola arvensis Murray in growth chambers and in shading cages outdoors at different irradiance levels was compared. Leaf area and shoot dry weight were lower outdoors than in growth chambers at similar irradiance and temperature. A simulation model with temperature and irradiance responses derived from growth-chamber experiments was used to test whether outdoor growth could be estimated properly. The correlations of the regressions between simulated and measured values of leaf area index (LAI) and shoot dry weight were high. However, with some exceptions, overestimations occurred, more for shoot dry weight than for LAI, and more for 100% daylight than for lower irradiance. The reasons for this are discussed.

Kirsten Semb Tørresen

Papers

Autumn growth of Elytrigia repens, Cirsium arvense and Sonchus arvensis at high latitudes in an outdoor pot experiment

Autumn growth of three perennial weeds at high latitude benefits from climate change.

Production systems and plant protection requirements in cereals: a model analysis of long-term effects

Growth of crop and weeds in growth chambers and outdoors.