WHAT ARE THE ALTERNATIVES TO CONTENTIOUS INPUTS IN ORGANIC POTATO CROPS?

POTATO

Organic-PLUS (O+) is an EU Horizon 2020 project involving 25partners in 12 countries (EU and non-EU), working to findalternatives to some of the contentious inputs currentlypermitted in certified organic production, including copperfungicides, mineral oils and sulphur, with a special focus onperennial Mediterranean crops such as citrus and olives, andgreenhouse crops like tomato and aubergine.

Pathways to phase-out contentious inputs from organic agriculture in Europe

Visit our website www.organic-plus.netFollow us on Twitter @OrgPLUSresearch

Judith.Conroy@coventry.ac.ukProject Manager

Ulrich.Schmutz@coventry.ac.ukPI (Principal Investigator)

This project has received funding from the EuropeanUnion’s Horizon 2020 impact and innovationprogramme under grant agreement No. 774340

Pathogens are generally controlled in organic potatocrops through repeated sprays of copper-based products.The demonstrated noxious effect of copper on soilmicrobial communities and other soil fauna has led toregulatory restrictions of its use. Copper for cropprotection purposes was permitted at a maximum rate of6 kg/ha/yr in the EU until the end of 2018, reduced to 4kg/ha/yr from January 2019. Several northern Europeancountries have, however, banned copper use entirely.

According to interviews conducted with experiencedadvisors as part of the Organic-PLUS project in 2018, theold limit was widely regarded as acceptable by Europeanpotato growers, while the new one may causeshortcomings under severe infections. Many alternativesto reduce or replace copper are under development, butfew are currently available on the market.

Potato is cultivated in most European countries, for usefor fresh consumption, for processed food products(French fries, crisps, dehydrated mashed potatoes…) andas a source of high-quality starch for a wide range ofindustrial purposes. Since potato is vegetativelypropagated, seed tuber production is a specific specialtycrop, with high sanitary requirements. Potato is primarilyan open-field crop, although early potatoes, planted andharvested very early in the season, are often grown underplastic covers for part of their cycle.Potato yields are compromised by a range of pathogensand pests which limit productivity in the field and canaffect tuber quality. Among the most problematic are lateblight (caused by Phytophthora infestans), early blight(caused by Alternaria spp.), and several virusestransmitted by insects.

This factsheet provides an overview of some alternative treatments and methods to replace or reduce the use ofcontentious inputs (namely copper and mineral oils, as sulphur is not used in organic potato production) that are used tocontrol diseases and pests in potato crops. Alternative compounds cannot be considered as one-for-one substitutes ofcontentious inputs, but should be integrated within more complex strategies for crop protection. In general, plant healthshould rely on preventive and indirect care measures in preference to off-farm inputs. The choice of varieties adapted tolocal conditions, the use of resistant varieties and other general measures which ensure a resilient agricultural system,strongly contribute to reduce dependency on external inputs to control pests and diseases.

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2.3 Versioni

Per una maggiore versatilità è disponibile anche la versione verticale di sigillo e logotipo da utilizzare nel caso non sia possibile l’uso della versione orizzontale. Anche in questo caso la singola parte (A) viene usata per determinare la distanza tra sigillo e logotipo.

È possibile utilizzare il solo logotipo nella versione orizzontale qualora la dimensione del sigillo dovesse risultare più piccola delle dimensioni minime consigliate (vedi 2.5.1) o, nel contesto, la riproduzione del sigillo potesse risultare pleonastica e ridondante.

A

2.3.1 Sigillo e logotipo verticale

2.3.2 Logotipo orizzontale

WHAT ARE THE ALTERNATIVES TO CONTENTIOUS INPUTS IN

ORGANIC POTATO CROPS?

ALTERNATIVES TO MINERAL OILS

Mineral oils, if used, are applied to seed potato crops torepel insects and therefore avoid virus transmission.

Alternatives include:

• Organic oils (e.g. rapeseed oil)

• Plant defence stimulators

• Diatomaceous earth

• Potassium salts of fatty acids

• Biological controls

Main goals of Organic-PLUS in relation to potato

Based on practitioners experience, O+ will concentrate ondesigning and testing new, effective alternative systems fororganic potato protection based on a combination of hostresistance, biocontrol and forecasting models. It will alsodevelop specific knowledge regarding the joint control of lateblight and early blight, since simulations based on futureclimate scenarios predict a shift towards increasedoccurrence of the latter disease in Europe between now andthe end of the century.

ALTERNATIVES TO COPPER

The main use of copper in potatoes is against late blight.Alternatives to copper currently include:

Natural alternative formulations, applied to replace orreduce copper dosage, used alternately or in combinationwith copper. Some of them are included in Annex II toCommission Regulation (EC) 889/2008, permitted forplant protection in organic crop production:

• Plant extracts with biocidal activity and stimulatingeffects on plant defences, and herbal preparationsincluding decoctions (heated extracts) of nettle (Urticadioica) and horsetail (Equisetum ssp.);

• Biological control agents, with a variety ofmechanisms of action against fungal and bacterialpathogens and stimulating effects on plant defenses.Bacillus subtilis, B. amyloliquefaciens, Pseudomonasspp., Trichoderma spp., Pythium oligandrum andStreptomyces spp., are examples of BCAs currentlyavailable to growers;

• Plant defense stimulators, such as seaweed extracts,silicates or chitosan, a natural polymer obtained fromchitin and reported to be active against a variety ofmicroorganisms.

A number of resistant cultivars are available, for allmarket segments. Their resistance comes from differentphysiological mechanisms which can be highly effective ina wide range of environments.

Authors: Andrivon D., Abuley I.K., Grenville-Briggs L., HansenJ.G., Lehsten V., Katsoulas N., Liljeroth E., Kir A.

Photos: © INRA

10

2.3 Versioni

Per una maggiore versatilità è disponibile anche la versione verticale di sigillo e logotipo da utilizzare nel caso non sia possibile l’uso della versione orizzontale. Anche in questo caso la singola parte (A) viene usata per determinare la distanza tra sigillo e logotipo.

È possibile utilizzare il solo logotipo nella versione orizzontale qualora la dimensione del sigillo dovesse risultare più piccola delle dimensioni minime consigliate (vedi 2.5.1) o, nel contesto, la riproduzione del sigillo potesse risultare pleonastica e ridondante.

A

2.3.1 Sigillo e logotipo verticale

2.3.2 Logotipo orizzontale

SYSTEM SOLUTIONS

Individual alternatives listed above have often demonstratedonly partial efficacy when used individually as substitution forcopper sprays. Therefore, their performance needs to besupplemented with agronomic good practices to allow forsatisfactory copper-free management in integrated pestmanagment systems. Among these best practices are:

Crop rotations of at least three years, and preferably four orfive, to control soil-borne pests and diseases and managevolunteers;

Sanitation, through the use of certified seed tubers and themanagement of refuse piles next to the fields, to limitprimary inoculum within or close to the production fields;

The use of Decision Support Systems, predicting the risk ofinfection according to local weather and to host resistance,for optimal timing of in-field applications. These systems cannow be refined to take into account the pathogenicitycharacteristics of local pathogen populations and the modesof action of biocontrol solutions currently being developed.