Physical mode of action of fungicides and fungicide ... · Physical mode of action of fungicides...
Transcript of Physical mode of action of fungicides and fungicide ... · Physical mode of action of fungicides...
Physical mode of action of fungicides and fungicide alternatives used
against strawberry powdery mildew
Belachew Asalf, David M. Gadoury, Arne Stensvand
Control of powdery mildew
• Cultural practices • Host resistance• Biological agents • Non-chemical alternatives • Fungicides
Biochemical mode of action of two major fungicide groups against powdery mildew
• Sterolinhibitors (e.g. penconazol) inhibit specific enzymes important for the sterol production in fungi
• Strobilurines (e.g. kresoxim-methyl) inhibit mitochondrial respiration and energy production
Physical (and biochemical) modes of actionProtectant: Stops germination, germ tube growth, and penetration Curative: Stops or inhibits mycelial growth and colonizationEradicant: Stops or inhibits established infections
Developmental stages of P. aphanis (Photo: B. Asalf)
Here we have studied how the fungal growth is affected by the different fungicides and alternatives before and after infection and after the disease has become visible
Treatments (recommended rates applied)
Product Active compound
Water
Candit kresoxim-methyl
Topas 100 EC penconazole
Thiovit sulfur
Rapsolje (Askim) rape seed oil
JMS Stylet oil mineral oil
Silwet Gold polyether modified trisiloxan(an adjuvant)
Treatments
Detached leaflets of June bearing ‘Korona’ in Petri dishes on water agar
• Preventive - sprayed just before inoculation
• Curative - sprayed 48 h after inoculation
• Eradicative – sprayed after sporulation started, one week after inoculation
• Conidial viablity was tested using fluorescein diacetate (FDA) 48 hours after eradicative treatments.
Preventive Curative EradicativeCandit +++ ++ ++Topas +++ ++ -Sulfur +++ + +Rape seed oil - - -Stylet oil ++ - -Silwet Gold - ++ -
Conclusion from these trials
+++ high efficacy++ moderate efficacy+ some effect- No effect