The aim of the EU-financed research project „STOVE“ (Seed Treatments for Organic Vegetable Production) is to evaluate different methods potentially suited for seed treatment of vegetables in organic farming regarding their efficacy, to optimise these methods, and where feasible to combine them with each other. Scientists from seven European research institutions and a producer of organic vegetable seeds carry out the project

Amein, T.

Forsberg, G.

Groot, S.P.C.

Gullino, M.L.

Jahn, M.

Koch, E.

Krauthausen, H.J.

Kromphardt, C.

Roberts, S.J.

Schmitt, A.

Tinivella, F.

Werner, S.

Wikström, M.

Wolf, J.M., van der

Wright, S.A.I.

English

Wageningen Yield 

STOVE
A Project about seed treatment for 
organic vegetable growing 
Until the end of 2003 seed derived from conventional agriculture could be 
used in organic production. Based on a directive of the European Union 
this is not allowed anymore. Seed for organic production must itself be 
produced organically. This can cause problems if the desired seed is not 
available, or only available with impaired quality. 
A common reason for impaired quality is external or internal contamina-
tion with bacteria and fungi that affect plant stand or lead to a diseased 
crop. Whereas in conventional vegetable production chemical seed treat-
ments are allowed that control or reduce at least the fungal pathogens, 
organic seed producers and vegetable growers have hardly any effective 
method for seed sanitization at hand.
Project description
The aim of the EU-financed research project 
„STOVE“ (Seed Treatments for Organic Vegetable 
Production) is to evaluate different methods poten-
tially suited for seed treatment of vegetables in organic 
farming regarding their efficacy, to optimise these 
methods, and where feasible to combine them with 
each other. Scientists from seven European research 
institutions and a producer of organic vegetable seeds 
carry out the project. 
Three physical methods (hot water, hot humid air 
and electron treatment) and different biological 
 applications are being investigated. Treatment 
with warm or hot water has in the past been quite 
 frequently used for sanitization of contaminated cereal 
seeds. Treatments with hot, humid air and electron 
seed treatment have been developed for the same 
purpose. In cereals these methods are currently in the 
introductory phase or already in practical use. 
The biological applications comprise for example 
plant extracts, inducers of resistance and microbial 
preparations. Some of these agents are marketed for 
other uses, e.g. control of foliage diseases, but so far 
it is not known, if they are also effective against seed-
borne diseases. 
Trial methodology
Studies on seed-borne diseases require sufficient 
quantities of seeds naturally infected to high 
 percentages with the respective pathogens. The 
 vegetables / pathogens selected (see table) were there-
fore mainly determined by the available seeds. But 
even a clearly diagnosed high percentage of seed 
infection cannot guarantee that the disease actually 
develops. Often, certain environmental conditions, 
like prolonged periods of wetness are needed to allow 
transmission of the pathogen from the seed to the 
plant parts aboveground. 
The properties of the diseases play an important role 
for the lay out of the experiments and evaluation 
of the disease. For example, in case of the carrots 
seeds contaminated with Alternaria-fungi or lamb`s 
lettuce infected with Phoma efficacy of the seed 
 treatments can be well evaluated in seed trays in tests 
under controlled conditions: infested seeds do not 
 germinate, or the seedlings show damping-off. 
In case of Septoria-leaf spot of parsley execution of 
the experiments is more difficult because the seed 
infection has no effect on the health status of the 
seedling. Therefore, the efficacy of seed treatments 
against this disease can only be assessed in field 
 experiments based on leaf symptoms. 
The situation is even more complicated with the 
 bacterial diseases. In practice, a few infected plants 
can be the starting point for massive disease, especially 
with transplanted crops like cabbage. Therefore, 
the threshold for the tolerable degree of infestation 
of seeds can be 0.01% or even lower. The seeds 
Comparative testing in the greenhouse and in the field
hot water · hot humid air · electron - treatment  · microorganisms 
resistance inducers · plant extracts
Testing of combinations of selected physical methods with
selected microorganisms, plant extracts and resistance inducers
Hot water, hot air and
electron seed treatment
Optimisation 
for different 
pathosystems
Effect on  
seed vitality
Microorganisms, resistance  
inducers, plant extracts
Effects on seed-borne pathogens 
and plant growth
Species Pathogens present 
on the seeds
Diseases caused
Carrot Alternaria dauci 
and Alternaria 
radicina
Leaf blight and black 
rot
Carrot Xanthomonas 
hortorum pv. 
carotae
Bacterial blight
Parsley Septoria 
petroselini
Septoria-leaf spot
Cabbage Alternaria 
brassicae 
Dark leaf spot
Cabbage Xanthomonas 
campestris pv. 
campestris
Bacterial black rot
Lamb`s 
lettuce
Phoma 
valerianellae
Phoma damping off
Bean Colletotrichum 
lindemuthianum
Anthracnose
Pea Ascochyta pisi Pea blight, pod spot
Main vegetable seed lots used in the project
used in our study had an infestation level of 0.18%. 
Nevertheless, even with a high percentage of trans-
mission from the seeds to the foliage with this seed 
lot experimental batches of several thousand seeds 
would be required to get significant results concerning 
the protective effect of the applied seed treatments. 
Because of this, indirect methods (e.g. detection of the 
causal agents in leaf washings by plating on selective 
agar media) were included in the experiments with 
Xanthomonas-infected carrot and cabbage seeds.
Physical methods 
– effective, but not without problems
One aim of the project was to adapt the treatment 
parameters of the physical seed treatment methods 
mentioned above to different vegetable species and to 
optimise their effect on the pathogens. For most of the 
host-pathosystems studied effective physical treatment 
variants were identified. However, all physical methods 
have in common that they may have adverse effects on 
the seeds if applied at too high intensity. As a result, 
germination may decrease instead of increase. Because 
the sensitivity of seed lots varies even within the same 
vegetable species, there is no „standard treatment“. 
In order to find out the optimum treatment for a 
given seed batch, pre-tests with germination assays are 
necessary. 
Experiments specifically designed to study the effect 
of seed maturity showed that the latter has a strong 
 influence on the sensitivity of the seeds. In these 
experiments cabbage seeds were sorted based on their 
colour (the browner the seed coat the more mature 
the seed) into different maturity fractions, which 
were then exposed to hot water, hot humid air or 
electron treatment. Afterwards, the germinability was 
determined. The results clearly showed that the seeds 
reacted to the hot water and hot humid air treatment 
the more sensitive the more immature they were.
Biological treatments – more efficacious in 
the greenhouse than in the field ?
In the greenhouse tests suitable biological treatments 
were identified for some of the studied vegetable- 
pathosystems. They included agents from all 
categories, i.e. plant extracts, microorganisms and 
inducers of resistance. 
Most of the results still require confirmation under 
field conditions, but the data available so far indicate 
that the efficacy of the biological treatments is often 
better in the greenhouse than in the field. In contrast, 
performance of the physical treatments under 
controlled conditions and in the field appears to be 
largely comparable.
A.	 	Spore-forming	structures	of	the	fungus Phoma 
valerianellae	on	the	surface	of	a	germinating	lamb`s	
lettuce	seed.
B.	 	Lamb´s	lettuce	seedling	killed	by	seed-borne	infection	
with	P. valerianellae
STOVE (Seed Treatments for Organic Vegetable 
Production) is supported by the European 
Commission, Brussels, Belgium, via Framework 
Programme 5, Key Action 5., Subsection 5.1.1: 
Sustainable Agriculture; New and improved produ-
ction and farming systems. The project-number is 
QLK5-CT-2002-02239.
The project started on 1 March 2003 and ends 30 
September 2006
Participants 
Dr. Eckhard Koch, Dr. Annegret Schmitt, Petra Zink, 
Dr. Marga Jahn, Dipl. Biol. Carola Kromphardt
Federal Biological Research Centre for Agriculture and 
Forestry, Institute for Biological Control and Institute 
for Integrated Plant Protection
Dr. Steven P.C. Groot, Dr. Jan. M. van der Wolf 
and Mrs. Patricia van der Zouwen, Plant Research 
International, Wageningen, The Netherlands
Dr. Sandra Wright, Dr. Tahsein Amein, 
Göteborg University, Sweden
Dr. Mariann Wikström, Dr. Rolf Stegmark,
Findus R&D, Sweden
Dr. Sigrid Werner, HILD Samen GmbH, Germany 
and Dr. Jan van den Berg, Nunhems Zaden, 
The Netherlands
Dr. M. Lodovica Gullino, Dr. F. Tinivella, 
AGRINNOVA, Italy
Dr. Steve Roberts, HDRA, Ryton Organic Gardens, 
UK
Sub-contractors
Dr. G. Forsberg, SEEDGARD AB, Sweden
Dr. H. J. Krauthausen, DLR Rheinpfalz, Germany
Dr. Ing. Olaf Röder, Fraunhofer Institut, Germany
Co-ordination
Dr. Eckhard Koch & Dr. Annegret Schmitt
Federal Biological Research Centre for Agriculture and 
Forestry, Institute for Biological Control, Heinrichstr. 
243, D-64287 Darmstadt
E-mail: e.koch@bba.de, a.schmitt@bba.de
 
Homepage
For further information, please see the project 
homepage at http://www.stove-project.net/
Facts on STOVE
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STOVE: Seed treatments for organic vegetable production

Wolf, van der, J.M.

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STOVE: Seed treatments for organic vegetable production

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