Tomatoville® Gardening Forums


Notices

Information and discussion regarding garden diseases, insects and other unwelcome critters.

Reply
 
Thread Tools Display Modes
Old June 1, 2023   #1
paradajky
Tomatovillian™
 
Join Date: May 2021
Location: Coastal Southern CA
Posts: 164
Default PM/fungus contradictory applications

Hi:

I read somewhere last year about contradictory applications when treating powdery mildew, and can't seem to find the information. I think it was something like don't use bleach or copper at least a week after using an oil-based treatment (e.g. neem or horticultural), or vice-versa. Spent a bit searching having trouble finding it again. Anyone know about this?

Background:
Here in coastal southern california it's been overcast and damp since mid april, with only a day or two of sunshine. We've even had some rain. Full on May Gray, now heading into June Gloom.

I got a late start on my tomato seeds just like last year, having sowed them about 6 weeks ago (mid-late April). They are outside and I've already pinched off a few leaves that had powdery mildew on them. I will be transplanting them to final growth spot this weekend. Squash okay so far. Something ate the cucumbers boooo. I sprayed the seedlings a few days ago with peroxide, it rained the next day, and I sprayed again with copper after the rains. Leaves look a little damaged but plants appear all right so far.

PM was one of the major diseases that took my tomatoes out last year after a very short harvest, despite good weather and weekly, alternating applications of 1.5% hydrogen peroxide and neem oil. For sure took out my cucumbers and squash, having only one short harvest. This year I'm trying copper and peroxide. I might put bleach in the rotation, or maybe consider the biofungicide method. I read through the entire bleach thread last year and maybe that's where I read about the contradictory application.

Thank you for your time!
paradajky is offline   Reply With Quote
Old June 2, 2023   #2
VirginiaClay
Tomatovillian™
 
Join Date: Jul 2019
Location: Virginia, USA
Posts: 139
Default

You can't use sulfur and neem oil (or any other oil) within 14-21 days of each other. It causes leaf burn.
VirginiaClay is offline   Reply With Quote
Old June 2, 2023   #3
paradajky
Tomatovillian™
 
Join Date: May 2021
Location: Coastal Southern CA
Posts: 164
Default

Awesome, thank you!!
paradajky is offline   Reply With Quote
Old June 3, 2023   #4
KarenO
Tomatovillian™
 
KarenO's Avatar
 
Join Date: Oct 2012
Location: Vancouver Island
Posts: 5,931
Default

When it comes to dealing with powdery mildew, the treatment approach is not very effective in general. Sulphur, neem, baking soda, milk etc all can provide some reasonable effectiveness in preventing or at least slowing down the development of the disease along with other good cultural practises like improving airflow, keeping foliage dry, where possible, etc. but none of them are very effective in my opinion to treat existing disease.
Resistant varieties and Preventative treatment will be the most effective approach when PM is going to be a yearly problem I think
KarenO
KarenO is offline   Reply With Quote
Old June 3, 2023   #5
paradajky
Tomatovillian™
 
Join Date: May 2021
Location: Coastal Southern CA
Posts: 164
Default

Thanks, I'm starting early with preventative treatment this year, even though a couple seedlings already had shown some PM here and there. I should have good airflow in this area, and since my ground-garden is on drip system and my tomatoes are in a bucket/gutter system, foilage stays dry except for the daily coastal dew. Until june gloom is over.



I will look into PM resistant varieties for next season, thank you for the tip Hopefully there are some dwarf varieties!
paradajky is offline   Reply With Quote
Old June 3, 2023   #6
KarenO
Tomatovillian™
 
KarenO's Avatar
 
Join Date: Oct 2012
Location: Vancouver Island
Posts: 5,931
Default

Another approach may be just to wait a bit longer to plant. If seedlings are not growing well and getting diseased early in the season it may be worth a try to either delay or stagger your plantings until the cool foggy time is over
My dwarfs seem to have done well in my cool spring nights
KarenO
KarenO is offline   Reply With Quote
Old June 6, 2023   #7
paradajky
Tomatovillian™
 
Join Date: May 2021
Location: Coastal Southern CA
Posts: 164
Default

Interesting strategy. I might start a few from seed now just to see what happens, since it feels like our warm season has shifted forward a few months here in southern california (relatively speaking...). Hmmm.
paradajky is offline   Reply With Quote
Reply


Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump


All times are GMT -4. The time now is 10:18 AM.


★ Tomatoville® is a registered trademark of Commerce Holdings, LLC ★ All Content ©2022 Commerce Holdings, LLC ★