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Pear sensitivity to neem oil?

Posted by Tim Bates 
Pear sensitivity to neem oil?
April 29, 2013 08:29PM
Communist alert! I'm not 100% sure...but 2 days after applying the third holistic spray ... I found 8 out of 10 comice pears had serious burn (looking very phytotoxicity like) all 5 of Flemish Beauty leaves had turned brown and shrivelled and my one Orca pretty much fried. However 2 Comice were completely unaffected just one row over. All other varieties (Bartlett, Bosc, D'anjou, Winter Nellis, Seckel and Buerre Hardy) completely unscathed. Looking for another cause, I had just spread lime the day before the Pulse spray and it was pretty windy at times and lime dust was flying around--but how to explain those 2 unaffected Comices??? Hot Days? Well, you Eastern types tell me. The day I spread lime (I know---you're supposed to spread it in late Fall, but it is so expensive and we had just enough bucks in Late march) it was a high of 70 F and the day of spray 62--then 62 --52 degrees. I don't think that was too hot.

On a happier note, I have to search high and low to find ANY scab on the pears!!! This is astounding as I had 95% damage on Bartletts last year and plenty (40-60%) on the other varieties. Even on the 15 trees that did not get sprayed with sulphur (the others got 2 Lime sulphur/micronized sulphur combo sprays). And the leaf shine--it's so bright it hurts your eyes on sunny days---really. I have found that pears "respond" to foliar sprays more visibly than apples do.

I am looking for others of you who have a fair amount of pears in your mix (I have an acre and change) to compare notes with.

The Apple Farm
Zone 8b in California



Edited 1 time(s). Last edit at 04/30/2013 08:02AM by Michael Phillips.
Re: Pear sensitivity to neem oil?
April 30, 2013 08:11AM
I've seen a degree of this, Tim, in that spotting of pear leaves happens more readily than apple following a spray mix that includes neem. Generally, I do put it down to temperature-induced damage but it's also possible to spray too heavily on a particular branch/tree and thus up the gross concentration of fatty oils on plant tissues . But what you describe sounds quite worse. The fact that not all varieties had this issue -- and that Comice actually showed both sides of the cheek -- does make things hard to figure. Maybe you have to use less than a 0.5% concentration for neem oil in the pear spray when foliage and fruitlets alike are fresh and tender? The use of liquid fish also should be considered, for its oil component certainly ups the ante yet again.

The other question to be asked here concerns the time window when oil can cause phytotoxic damage. And here I think we're not just talking about neem oil but any fat and/or horticultural oil. I've assumed four to six hours before temps rebound into the 80s might be "safe" and thus advise growers do evening sprays during warm spells, if really necessary. That time lag factor of damage showing up 24 to 48 hours later is compelling as well. What do we need to understand here?

Lost Nation Orchard
Zone 4b in New Hampshire



Edited 1 time(s). Last edit at 04/30/2013 08:23AM by Michael Phillips.
Re: Pear sensitivity to neem oil?
May 08, 2013 09:11PM
I have seen this on Flemish Beauty for a few years; only this spring have I started to suspect the neem. This year all the spur leaves on the Flemish Beauty are completely black, vegetative leaves look fine so far, but they came out later, so I am suspecting that it came from the first (april 28) spray: that was 1 oz neem/1 oz natural dish detergent and seaweed in 1 gal water rate at tight cluster. Bosc and Harrow Delight essentially fine (scarce spotting). Weather has been dry and unusually warm/hot. It is leftover neem from last year (Ahimsa), though I don't know as that makes a difference.

Varietal difference is quite dramatic.

I did not take particular notice of these symptoms (or absence of symptoms) before first trying neem several years ago, so can't for sure blame the neem, but next year I will definitely skip the neem on part of the tree to test.

Jim Gallott
New Haven, VT USDA Zone 5a
Re: Pear sensitivity to neem oil?
May 14, 2013 01:54PM
Interesting. The Flemish Beauty has bounced back much better and faster than Comice--which is recovering---all new growth looking real good. Pretty much lost all Comice fruit, but some still on the Flemish. Will learn more next year. Weather here dry and warm also.

The Apple Farm
Zone 8b in California
Re: Pear sensitivity to neem oil?
April 09, 2014 11:01AM
Hello, we've had a bad time of it with Neem on pears once it warms up. We don't do this now....Susan
Revisit Blackening leaves on pears
May 09, 2014 01:57PM
Well, in this second year of a full on Neem and Fish program, the blackening leaves on Comice and Flemish Beauty have returned---this time on all of them instead of a few. But not as severe as last year's damage--only one tree nearly defoliated. Since I have only seen this a very few times in 30 years, I can only suspect the Neem may be the culprit in exacerbating the problem. It happened this year several days after 3rd Neem spray (same as last year except it happened immediately after 3rd spray) and on only 2 trees---but over the next week all trees were afffected. Also from the tractor seat I cannot see a single pear on any of the Comice. Will confirm this later as fruit sizes. Checking on some old soil tests I usually come out a little low on potassium, but not real low. Will reread your comments on that. Next year will mark many of the trees and try to avoid them at least for the 3rd spray. Comments...ideas?
Re: Pear sensitivity to neem oil?
May 23, 2014 07:09PM
Let's say a guy gets ramped about pear blister mite. In this case, a new tree from a nursery introduces this pest to the farm ... that nursery won't be named ... yet such is how such things happen. Last year this young tree gets 'neemed' hard (now there's a new verb for y'all!) yet dammit it, the mites subsequently move onto a productive tree this new season. So that guy - who also will not be named (smiley thing) - blasts the hell out of the young tree source and the reddened shoot growth on the newly afflicted. Neem, after all, is systemic and will impact the molting cycle of blister mite. Said guy now realizes the result of his newest obsession. Excessive pear spraying means higher fatty acid concentration ... thus pear leaves burn. Oh, indeed, they do burn. Said guy now curses his narrow-sighted idiocy.

My advice: Spray pears "lightly" with the o.5% core recipe, or if you have a significant amount of pears, and have experienced leaf burn, cut the neem rate by half. All the more so after bloom.

And if you feel obsessed, spray the sheep. Or maybe the neighbor. Pears have a sensitivity and that's a fact!

Lost Nation Orchard
Zone 4b in New Hampshire
Re: Pear sensitivity to neem oil?
May 24, 2014 12:26PM
Update--There are indeed no comice or flemish beauty fruit on the blackened trees--NOthing! Unnoticed from the tractor seat 2 comice did not blacken up and are loaded with fruit--8-10 year olds. Go figure. last year I did not pay enough attention to whether the blackened trees had or tried to set some frui but dropped it early in the game (come to think of it I can't say for sure about this year either). Will need to pay close attention at bloom time in 2015. It makes one wonder if the tree knows it's gonna have it ahead of time and gives up it's potential crop early on. Talk about systemic! Gosh Michael, I don't know nuthin' 'bout pear blister (except on my fingers when thinning too hard) mites, but I didn't know about flatheaded borer until you introduced me in your book---I hope the mite doesn't follow suit and find my farm.
Re: Pear sensitivity to neem oil?
April 03, 2015 09:01AM
Has anyone tried spraying pears with smaller neem concentrations (0.25-0.5%) after petal fall, with daytime temps in the 80's?

Zone 6a in North Carolina
Re: Pear sensitivity to neem oil?
April 05, 2015 12:48PM
I would volunteer for that one--except it's too late! Of course I did not reread this thread before the first two neem spring sprays..or I probably would have tried it from Michaels earlier suggestion. Comice and Flemish Beauty are blackening and I have not done 3rd spray yet...but did a competitive boost (no Neem or fish) Of EM, Mollasses, Kelp, and compost tea yesterday and decided to not hit those trees because of nervousness...probably would not have mattered as fatty acids seem to be the culprit. Will begin 2016 notes and ideas today and will hopefully pay heed next year.

The Apple Farm
Zone 8b in California
Re: Pear sensitivity to neem oil?
May 27, 2015 09:57PM
Several grape varieties may also be sensitive to a .5% dilution including Worden and Allwoods, we noticed this burn after spraying on early green shoots with emerging fruit clusters. Still love the neem/karanja just the same. Will back off to .25%.
Re: Pear sensitivity to neem oil?
May 28, 2015 06:07AM
I find this all very interesting -- of course I find everything on this site very interesting. First, pears are very resistant to horticultural oils, (standard app cautions apply), and is recommended as an effective preventative against pear psylla at 1% through the summer. But Hort oils tend to be pretty refined and don't have any nasty stuff, much less good stuff like FAs. Second, I've re-read the threads and am wondering what else may have been applied prior to or in tank mix with the neem in addition to any fish. While it seems that the conclusion is that fatty acids are the culprit, Cueva also has fatty acids -- has anyone seen the same effect from Cueva? Oils are known to be penetrants (helps things get into the leaf) and so any number of other materials could also be at work - (yes/no/maybe?) - exacerbated by the oil. Finally, I am wondering whether any of the Aza-type (cleaned up neem) products also promote any of the leaf burn you're seeing with pure neem. Or have they been so stripped of any goodness that they wouldn't hurt a fly? It just seems that 0.5% or less would be harmless (for the most part). And how could anything good, like fatty acids, be bad at such a low concentration. In essence, my question is what makes pears so susceptible to neem oil induced leaf burn, when they are virtually immune to hort oils at higher concentrations? I know more questions than answers......What about karanja?

Mike Biltonen, Know Your Roots
Zone 5b in New York
Re: Pear sensitivity to neem oil?
April 22, 2016 01:35PM
On 4/19/2016, I applied my second holistic spray in the morning using a 2/3 concentration of Neem. Temps never got above 80. Here are my findings:
Within 3 days, Moonglow and Potomac show extreme leaf burn, Moonglow blossoms are toast. Flemish Beauty experienced some burn but not as bad as the other two.

The unaffected pears (so far) are Harrow Delight, Anjou, Seckel, Magness, Sunrise, and Shenadoah. I missed spraying the Comice pears by mistake which was fortuitous based on comments from previous posts.

The next holistic spray will use 1/3 the recommended amount. Will update my finds post spray #3.

Joanne Patton, Squire Oaks Farm
Zone 6A, Northern Virginia
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