downy mildew

[wood1954]

i was checking my new growth and already found some downy mildew on my marquette grapes. I've sprayed with mancozeb, captan and tebuconazole twice, so i was surprised to see two leaves infected. i know only two, but it means it's out there already. The plant that i found it on was next to a plant that was so infected last year that it died. I'm having cataract surgery tomorrow so wont be able to spray again for a few days. I really want to stay on top of the mildew this year.

 

[David Violante]

I’ve used mancozeb and stylet oil. If you end up deciding to use a styler oil also, you have to wait on the application if you’ve used captan. Here’s a good article from UGA Extension.

Powdery and Downy Mildew Recommendations | UGA Extension Viticulture Blog

 

[Cynewulf]

It might help to know more about your spray protocol (timing, dose, etc.). Are you mixing all of those together? Are you disposing of leftover spray or keeping it? I spray with mancozeb (downy and black rot) and sulfur (powdery) every 7-10 days early in the season for the first 6 applications or until the 66 day phi. Then I switch to captan (downy) and immunox (black rot and powdery) for the next 5 applications, then just captan and sulfur based on the weather and disease pressure.

 

[VinesnBines]

Okay; someone give me some confidence.

Last week I sprayed with Bionide Fruit tree spray and neem oil. I was too lazy to open the big bag of mancozeb. The fruit tree spray has 11.75 % captan. The neem oil is not paraffitic oil or stylet oil but still OIL.

I sprayed lightly on Wednesday with a three gallon hand sprayer - nine gallons for over one acre. I used the label amounts of fruit tree spray and by Saturday I didn't notice any damage. I did notice that every vine was doubling growth in two days. I hope I have not cooked my foliage or worse, killed my vines.

I've learned a lot of lessons today. Even though I read the restrictions, I need to read OVER and OVER. Second, don't be lax and use the mancozeb when I'm supposed to use.

Please don't tell me that I have killed the vines or destroyed the crop. If that is your response, don't post it.

(Also, I'm out of town for a couple weeks so I can't run to the vineyard to look) Anyway, I understand there is not much I can do now but learn the lessons.

 

[Cynewulf]

Okay; someone give me some confidence.

Last week I sprayed with Bionide Fruit tree spray and neem oil. I was too lazy to open the big bag of mancozeb. The fruit tree spray has 11.75 % captan. The neem oil is not paraffitic oil or stylet oil but still OIL.

I sprayed lightly on Wednesday with a three gallon hand sprayer - nine gallons for over one acre. I used the label amounts of fruit tree spray and by Saturday I didn't notice any damage. I did notice that every vine was doubling growth in two days. I hope I have not cooked my foliage or worse, killed my vines.

I've learned a lot of lessons today. Even though I read the restrictions, I need to read OVER and OVER. Second, don't be lax and use the mancozeb when I'm supposed to use.

Please don't tell me that I have killed the vines or destroyed the crop. If that is your response, don't post it.

(Also, I'm out of town for a couple weeks so I can't run to the vineyard to look) Anyway, I understand there is not much I can do now but learn the lessons.

Not sure what your concern is if you applied last Wednesday and haven’t seen damage: the neem oil or the captan? Was it over 90 degrees when you applied the oil? I’d be concerned that you need to protect against black rot right now and neither captan nor neem oil will give you coverage against it.

 

[balatonwine]

two leaves infected

Two leaves? Really..... The world is not perfect. And a little damage can be tolerated. Also known as "Integrated Pest Management"

https://www.epa.gov/safepestcontrol/integrated-pest-management-ipm-principles
Integrated Pest Management

https://www.cdc.gov/nceh/ehs/Docs/Factsheets/What_Is_Integrated_Pest_Management.pdf

Two leaves may be an indicator, but till you confirm actual pest loads, it means little. Almost a comedy. Nip them off and toss them in the garbage. Then monitor your vineyard till you see real issues that are of concern. Contact your local Ag/Uni extension to help you determine what is to be concerned about. And I suspect they may laugh at "two leaves".....

 

[VinesnBines]

Not sure what your concern is if you applied last Wednesday and haven’t seen damage: the neem oil or the captan? Was it over 90 degrees when you applied the oil? I’d be concerned that you need to protect against black rot right now and neither captan nor neem oil will give you coverage against it.

I am therefore I worry. I'm trying so hard to get it right and thought I was going well this year. I'm not at all concerned about black rot yet. The temps were well below 90; I sprayed in the morning and the high was about 80 by 3 pm.

I probably could have waited on spraying but I wanted to get on the cycle. I'm worried the oil will allow the captan to damage the foliage and the vines. I'm hoping that there is so much new growth that any damage will be negligible. I noticed that a few vines that ware chewed up by the deer had bloom clusters left and leaves were sprouting, so I have hope.

Thanks for being sympatric.

 

[Cynewulf]

I am therefore I worry. I'm trying so hard to get it right and thought I was going well this year. I'm not at all concerned about black rot yet. The temps were well below 90; I sprayed in the morning and the high was about 80 by 3 pm.

I probably could have waited on spraying but I wanted to get on the cycle. I'm worried the oil will allow the captan to damage the foliage and the vines. I'm hoping that there is so much new growth that any damage will be negligible. I noticed that a few vines that ware chewed up by the deer had bloom clusters left and leaves were sprouting, so I have hope.

Thanks for being sympatric.

Ah, sorry I just realized what you were getting at. I don’t use oils so I didn’t realize that captan can potentially become phytotoxic when mixed with it; I’d only heard about sulfur. The Bonide Captan that I spray with is 48.93% so a significantly higher dose than what you applied. Looks like there are different opinions out there on whether it’s really a problem or not so maybe you’re good. Hoping for the best…

 

[David Violante]

@VinesnBines I think if you sprayed last week you would have seen something by now to indicate whether or not things went sideways. As Cynewulf indicated it's a lower dosage as well. Hoping for the best as well...

 

[VinesnBines]

@VinesnBines I think if you sprayed last week you would have seen something by now to indicate whether or not things went sideways. As Cynewulf indicated it's a lower dosage as well. Hoping for the best as well...

Thanks so much. This looks to be a decent crop and I've been kicking myself across the county. Nothing like stupid mistakes to teach a valuable lesson.

 

[David Violante]

Don’t beat yourself up too much... it could really not be a big deal. You indicated you lightly sprayed and saw doubled growth. Enjoy your trip and when you’re back pick yourself up and keep going with the knowledge of a better approach.

 

[VinesnBines]

Don’t beat yourself up too much... it could really not be a big deal. You indicated you lightly sprayed and saw doubled growth. Enjoy your trip and when you’re back pick yourself up and keep going with the knowledge of a better approach.

Thanks! We had over three inches of rain yesterday so I expect to get back and have trouble finding the trellis for the new growth. Thanks again for sympathy and support. I'm hoping the vines just shrug it off.

Sorry for hijacking the thread.

 

[wood1954]

Two leaves? Really..... The world is not perfect. And a little damage can be tolerated. Also known as "Integrated Pest Management"

https://www.epa.gov/safepestcontrol/integrated-pest-management-ipm-principles
Integrated Pest Management

https://www.cdc.gov/nceh/ehs/Docs/Factsheets/What_Is_Integrated_Pest_Management.pdf

Two leaves may be an indicator, but till you confirm actual pest loads, it means little. Almost a comedy. Nip them off and toss them in the garbage. Then monitor your vineyard till you see real issues that are of concern. Contact your local Ag/Uni extension to help you determine what is to be concerned about. And I suspect they may laugh at "two leaves".....

I know a few leaves aren’t a problem just wanted to make people aware of the danger of not spraying, last year I lost a lot of grapes because I didn’t spray just before and just after bloom.

 

[wood1954]

It might help to know more about your spray protocol (timing, dose, etc.). Are you mixing all of those together? Are you disposing of leftover spray or keeping it? I spray with mancozeb (downy and black rot) and sulfur (powdery) every 7-10 days early in the season for the first 6 applications or until the 66 day phi. Then I switch to captan (downy) and immunox (black rot and powdery) for the next 5 applications, then just captan and sulfur based on the weather and disease pressure.

I mixed them all together and spray in the morning. I mix fresh every time. The vineyard actually looks pretty good best year yet. After a lot of reading I’ve changed my spray program to be more like yours, less complicated and less expensiv.

 

[balatonwine]

I know a few leaves aren’t a problem just wanted to make people aware of the danger of not spraying, last year I lost a lot of grapes because I didn’t spray just before and just after bloom.

Good point. While not clear in your original post, this is indeed an issue new wine growers may miss and and issue that deserves special tagging so they can avoid grief. Been there.