Management of crazy roots by cultivation techniques
Wendy Vanlommel*, Céline Gilli, Sandrine Eberle, Alain Guillou, Bart Van Calenberge
15/Jan/2019 Symposium: monitoring and management of current and
emerging plant pests and diseases in tomato and bell pepper 1
*Research Centre Hoogstraten
Voort 71, B‐2328 Hoogstraten (Meerle) Tel.: +32 (0) 3 315 70 52
Wendy.Vanlommel@proefcentrum.be
www.proefcentrum.be
Introduction
• Main symptoms
• Excessive root development within and around the plant cube and the slab surface
• More vegetative plant growth
• Yield losses up to more than 10%
• Management of hairy root disease (HRD) difficult due to large diversity between rhizogenic agrobacteria (RA)
strains and biofilm formation.
• Reduction of symptoms expression by cultivation techniques is one possibility.
15/Jan/2019 Symposium: monitoring and management of current and
emerging plant pests and diseases in tomato and bell pepper 2
Overview cultivation techniques
Severeness of symptoms can be influenced by the choice of:
• Before the growing season
• Substrate
• Rootstock
• Cultivar
• During the growing season
• Generative steering: climate and irrigation
• Generative measures: cultivation techniques
15/Jan/2019 Symposium: monitoring and management of current and
emerging plant pests and diseases in tomato and bell pepper 3
Overview cultivation techniques
Severeness of symptoms can be influenced by the choice of:
• Before the growing season
• Substrate
• Rootstock
• Cultivar
• During the growing season
• Generative steering
• Generative measures
15/Jan/2019 Symposium: monitoring and management of current and
emerging plant pests and diseases in tomato and bell pepper 4
1. Substrate
• A drier substrate gives less symptoms
• Depending on the chosen substrate, a drier root environment can be created more
easily:
• Polyurethane foam and Perlite are airy and drain easily (but also less security for irrigation management)
• A higher rockwool slab results in a drier environment for the roots at the top of the slab.
15/Jan/2019 Symposium: monitoring and management of current and
emerging plant pests and diseases in tomato and bell pepper 5
0 5 10 15 20 25 30 35 40 45
Rockwool 10 cm
Rockwool 7.5 cm
Pe rc en ta ge sl ab s wi th sy mp to ms (% )
1. Substrate
• Organic slabs made of different types of peat and coco fibres contain a wide range of microorganisms, which probably counteract RA
• Trial with different tomato cultivars
• 2 Substrates:
• Rockwool
• Grow Bag
Thickening of the stem base is prevented (excessive
root growth is rare)
15/Jan/2019 Symposium: monitoring and management of current and
emerging plant pests and diseases in tomato and bell pepper 6
f f
b bc bc
df
cd
a a a
10 12 14 16 18 20 22 24 26 28
Prunus ‐ Grow Bag
Prunus ‐ Rockwool
Balancan ‐ Rockwool
Merlice ‐ Rockwool
Rebelski ‐ Rockwool
St em di am et er (m m )
No symptoms
Symptoms
1. Substrate
• Conclusion
• A drier substrate gives less symptoms
• A certain microbial community in the slabs can counteract RA
15/Jan/2019 Symposium: monitoring and management of current and
emerging plant pests and diseases in tomato and bell pepper 7
2. Rootstock
• Scorpio (eggplant cultivar)
• 2 Rootstocks:
• Beaufort (more generative)
• Kaiser (more vegetative)
• Measurements:
• Root development assessment with scoring system 1‐5
Severeness of symptoms less
pronounced with more generative rootstock
15/Jan/2019 Symposium: monitoring and management of current and
emerging plant pests and diseases in tomato and bell pepper 8
b a B A
0 1 2 3 4 5
Kaiser Beaufort
A m ount of roots at the top (s co re 1 ‐ 5)
No symptoms
Symptoms
Symposium: monitoring and management of current and emerging plant pests and diseases in tomato and bell pepper
2. Rootstock
• Plaisance (tomato cultivar) on coco fibre slabs
• 6 Rootstocks:
• Ranked from vegetative (bottom) to generative (top)
Prevention of symptoms not possible BUT severeness of symptoms strongly reduced
0 10 20 30 40 50 60 70
Optifort Emperador Maxifort Beaufort Unifort Arnold
Percentage slabs (%)
No symptoms Few symptoms Severe symptoms
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GEN
VEG
2. Rootstock
• Conclusion
• A more generative rootstock results in a reduction of severeness of symptoms caused by HRD.
15/Jan/2019 Symposium: monitoring and management of current and
emerging plant pests and diseases in tomato and bell pepper 10
3. Generative measures
• Tomato trial
• Rebelski (tomato cultivar), grafted on Maxifort
• 4 Treatments:
• Negative control: plants without symptoms
• Positive control: plants with symptoms, but without interference
• Opening slabs
• Pruning leaves
• Measurements:
• Yield
• HRD incidence (root development assessment every 2 weeks with scoring system 1‐5)
• Two consecutive years (2015‐2016)
15/Jan/2019 Symposium: monitoring and management of current and
emerging plant pests and diseases in tomato and bell pepper 11
3. Generative measures
• Tomato trial
15/Jan/2019 Symposium: monitoring and management of current and
emerging plant pests and diseases in tomato and bell pepper 12
a b A
B
a
A b
B
0 5 10 15 20 25 30 35 40 45
2015 2016
Average sum of root scores (score 1‐5)
a
A
b
B a
A
b
B
15 16 17 18 19 20 21 22 23 24 25
2015 2016
Yield (kg/stem)
No symptoms
Symptoms ‐ no interference Symptoms ‐ opening slabs Symptoms ‐ leaf pruning
Opening of the slabs is a good measure to reduce/prevent symptoms and yield losses on tomato
Prevention of symptoms confirmed on eggplant
Symposium: monitoring and management of current and emerging plant pests and diseases in tomato and bell pepper
b B
a
A
c
B a
A
0 1 2 3 4 5
Beaufort Kaiser
A m ount of root s at the top (s co re 1 ‐ 5)
No symptoms
Symptoms ‐ no interference Symptoms ‐ opening slabs Symptoms ‐ leaf pruning
3. Generative measures
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• Eggplant trial
• Scorpio (eggplant cultivar), grafted on Beaufort/Kaiser
• 4 Treatments:
• Negative control: plants without symptoms
• Positive control: plants with symptoms, but without interference
• Opening slabs
• Pruning leaves
3. Generative measures
• Explanation mechanism for opening of the slabs
• Trial with cucumber
• 3 Treatments
• Control
• Opening slabs – transparent cover
• Opening slabs
15/Jan/2019 Symposium: monitoring and management of current and
emerging plant pests and diseases in tomato and bell pepper 14
A transparent cover is not sufficient to reduce root growth
Reduction of root development by opening of the slabs is thus
primarily caused by a drier substrate and not by the light on the slabs
0 1 2 3 4 5
14/03/2017 7/04/2017 9/08/2017 13/10/2017
Am ount of roots (s co re 1 ‐ 5)
Control
Opening slabs ‐ transparent cover
Opening slabs
3. Generative measures
• Conclusions:
• Opening of the plastics of the slabs prevents yield losses after infection succesfully.
• Leaf pruning did not prevent HRD symptoms in the trials HOWEVER in combination with a more generative climate and irrigation strategy, leaf pruning will probably be able to prevent yield losses due to RA.
15/Jan/2019 Symposium: monitoring and management of current and
emerging plant pests and diseases in tomato and bell pepper 15
General conclusions
• Some cultivation techniques are able to reduce HRD symptoms
• A generative rootstock can reduce the severeness of the symptoms
• Choice of the slabs can reduce symptoms
• Opening of the slabs prevents symptoms and yield losses
• The effectiveness of the techniques is not influenced by the type of RA strain present (e.g. catalase activity) HOWEVER cultivation
techniques are not a solution on the long‐term!
• Biofilm formation not tackled
• No direct effect on disease
15/Jan/2019 Symposium: monitoring and management of current and
emerging plant pests and diseases in tomato and bell pepper 16
DRIER
ENVIRONMENT
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emerging plant pests and diseases in tomato and bell pepper 17
