Lactuca sativa is one species generally prone to infection by powdery mildew races. Can anyone tell me about some success they had in eradicating it off of a lettuce (or other) crop without (or with) the use of commercial fungicides? Has anyone used hydrogen peroxide or neem oil, and if so, what were the results? My crop is in a greenhouse setting, but any information will be helpful, thank you!
Most important is the prevention of infection from the air, media (soil), water, and direct contact with the carrier. I use silica powder and calcium to strengthen the epidermal layer of the plant, so that so the plants are not easily infected.
It was proven to prevent powdery mildew infection on Pogostemon cablin, sweet corn, Brassica rapa, Brassica chinensis, and Lactuca sativa. This simple method is also very effective for the prevention of anthracnose infection on solanaceae (Solanum lycopersicum, Solanum melongena, Capsicum annum, and Cucumis sativus) and powdery mildew on Zingiber officinale at higher ground plantation in Bogor, West Java, Indonesia. You can first apply 5 grams silica powder and 5 grams calcium for each plant, or you can apply another dosage at your medium (soil) which appropriate with your local condition...
Temperature and humidity also affect the risk of infection, and at the greenhouse it should be controlled.
Good luck...
Hi: Sulfur is very effective on powdery mildew, i have use it on other crops, but i have not use it on lettuce before .
Organic lettuce can be attacked by powdery mildew. If you irrigation with over head system the washing of the leaves will reduce powdery mildew which abounds in drier environments.
Make sure you get a good powdery mildew identification as difference mildews can be confused and your approach would vary based on pathogen identity. The controls for downy mildew and powdery are distinct and in some plant species there are different species and races of powdery mildew. Diagnosis is important.
Another way to combat powdery mildew is will biocontrol fungicide such as Bacillus subtulius serenade. Finally some workers have gotten good results with milk and others with bicarbonate application.
As Oadi Matny pointed out Sulfur can be used but it also can be burning and the timing and concentration needs attention. Lime sulfur was traditionally used to soften the phytotoxicity associated with the Sulfur. If you apply at sundown there is less issues with Sulfur burning. Sulfur can lead to acidification of the soil which may need to taken into consideration. Sulfur would probably be a better choice in alkaline environments than soil acid prone ones.
In some old acid soils the Silicon deficiency predisposes the high severity of powdery mildew. The Silicon when readily available stimulates an active and passive resistance mechanism. Some workers have gotten good results in controlling powdery mildew with compost tea but measures need to taken to eliminate any E. coli potential.
We are discussing lettuce grown in a sterile (root pathogen-free) hydroponic systems with sub-irrigation.
Thank you for your input, and I would appreciate as much detail as possible.
Dear Joseph In your conditions make sure you have the Silicon optimized in your hydroponic system.
Secondly I would use the serenade which ORMI approved.
Hi
I have studied about lettuce of virus diseases and survied lots of field every season(2 years).
I sometimes see the powder mildew on Lactuca sativa L. var. crispa and capitata the early spring and the late autumn.
I asked the growers whether use pesticids, They said no:)
But a grower used biological solution with bacteria...
Hi Zelyut...
Using Bioagent such as bacteria and fungus might not effective due to UV radiance of the sun light...
Many of bioagent may not tolerance of UV (especially in tropical area)...
The Serenade biofungicide is based on Bacillus subtilis noted for it resistance to extreme conditions based on endospore production. Some of these strains are endophytic and take up residence in the plants.. The efficacy of any of the suggested practices is best validated through programmed replicated trials that are well designed and analyzed for variance and separation of treatment means.
I am also not growing in a tropical environment, hence the greenhouse. My crop is growing in a heated glasshouse and is generally very dry. I have had success with a 1% H2O2 spray, which seems to have eradicated all inoculant, and I applied a foliar spray of potassium silicate after a couple of days. No new infections have been observed. Had my attempts failed, I definitely would have sought results from Serenade. Thank you all for your input, and feel free to continue to provide your perspectives.
As Oadi Matny mentioned, sulphur is a mean. It is generally non-toxic to animals and plants. The critical point is the way of application. If powder or a colloid suspension is applied, the distribution may not be uniform and local burns may occur if the concentration is too high. I remind a safe forgotten way, used 60 years ago in greenhouses: small electrically heated containers with about 100 ml of molten sulphur, which slowly evaporates, suspended from the c eiling. It is harmless, but effective. If not available on the market, it can be easily made by a skilled technician.
I am not sure if you are still interested in getting more responses but we used milk to control Powdery Mildew in kale. Check the attached scientific article. Good luck in your research.
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