Michael Phillips 55 days ago
ActivityRank: 396

Many of us depend on sulfur as the primary means of controlling fungal disease. Those who use excessive amounts don't seem to have the success of those making 2 to 4 well-timed applications of micronized sulfur based on wetting events. Yet there's a price to be paid here that we as organic growers should discuss more fully, methinks.

Sulfur use has a proven impact on yields. One good baseline here is Chuck Souther’s experience at Apple Hill Farm outside of Concord, NH. He maintained a 2 acre organic block for ten years in the midst of his IPM acreage. Comparative yields on McIntosh went down to 300-350 bushels per acre in the organic block from the 500-600 yield range in the IPM trees. Yields are absolutely subjective but here's a valid observation from the same place, same tree size, same spacing, same soil... the one big change being that heavy sulfur use was the principle dynamic introduced in the organic block. We know the same about lime sulfur: this formulation of sulfur is used as a thinner because it’s a photosynthetic inhibitor, thus causing fruitlets to be aborted.

Fruit finish is a relevant consideration as well. I think organic growers see more russeting regardless what we do, but here's an even more specific issue in which sulfur may play a role. I'm referring to the mysterious "red spot disease" that appears on yellow varieties, at least here in the East. The lenticels in the skin of the fruit likely become colonized by an opportunistic organism, and all the more so because skin growth has likely been aggravated by mineral fungicides (that point can be debated) or at the very least “good guy colonization” perturbed by the use of a fungicide. A chemical strobilurin like Pristine can take of the Botryosphaeria fungi and the like, so it’s been reported. Organic mineral fungicides apparently do not.

My current direction is away from sulfur -- I’m favoring the arboreal food web connection through the use of herbal nutrition and microbe diversity -- so it’s going to be interesting to see what happens as regards yields and fruit finish.

hgforganicapples 55 days ago
ActivityRank: 104

Michael, do you know how much total sulfur Chuck Souther was applying? Any lime sulfur? I'm convinced that lime sulfur works differently than sulfur (probably releasing hydrogen sulfide instead of sulfuric acid) and is much more phytotoxic.

I have been curious as to whether sulfur depresses yields, and at what spray rates. I have a row of Liberty trees which gets no sulfur between rows of Jonagold and Golden Delicious, which do. The Liberty yielded 51 bu from 8 semidwarf trees this year, about 6.4 bu/tree. The trees are planted at about 120 trees/acre, so that would be about 750 bu/acre.

The Jonagolds gave 64 bu from 11 trees, not quite 6 bu/tree. Alas, however, they had scab really bad in spite of my sulfur sprays. The scab itself definitely can depress yield (!), as I know from my no-sulfur Tydeman's Early trees which got scab for the first time and produced cracked fruit slightly larger than golf balls! The Jonagolds had decent size, but not great.

Meanwhile, Melrose trees which get sulfur gave 115 bu from 18 trees, again about 6.4 bu/tree, and Idared gave 130 bu from 18 trees or about 850 bu/acre. Both of those have gotten sulfur every year since 1989. Scab on those was much worse than I like to see last season, but not horrendous like the Tydemans. These trees bear alternately and had 50 and 32 bu respectively, last year. But Liberty also was down last year, at 22 bu.

So from this, it looks as though the sulfur-sprayed trees are doing as well as Liberty in terms of yield. Most years, they are free of scab (< 1%), but not in 2009!! Our site is not considered to be a good apple site, especially in terms of its marginally-drained soil.

In 2009 I sprayed with sulfur 7 times during primary scab season, using 6 lb sulfur/100 gal and spraying 150-200 gal/acre (on scab-susceptible varieties only). I also made 4 more sprays @ 4 lb/100 in the second part of the season, in a vain attempt to quell the scab tide. So more sulfur than usual was applied. Generally I have felt that the amount of sulfur I use is not quite over the "excessive" line, but perhaps close to it.

All this being said, of course I would like to spray less sulfur (and less, period!). After the complete scab failure of last season, I am ready to try out a program of neem oil and fish hydrolyate on part of the orchard--we'll see how it does under heavy spore pressure!

Best wishes to all,
Brian Caldwell

Doug Waples 54 days ago
ActivityRank: 54

No sulfur would be a great way to go (I hate spraying), but the two seasons I tried to get by without sulfur were disasters. My trees are densely planted and this contributes to the problem. I have had some rabit damage to the smaller trees due to the drifting snow and ice layer making it easier for bunnies to eat bark. I am looking to thin my orchard by 15% this spring to improve the airflow and keep up with my reduced use of lime-sulfur and continue with the neem-fish emulsion to support the habitat.

It is a quandry--there is not have enough site-specific data available to make a decision and we have to proceed based on philosophy. I plan to keep better records this season and will press on with reducing my dependence on sulfur.

Todd Parlo 54 days ago
ActivityRank: 64

Having done alittle poking around i have found a whole lot of studies over the last 50 years that show decreased yield due to lime sulfur use, but not elemental sulfur in and of itself. Chuck has been growing apples for a long time, and I trust he has good reason to believe that sulfur layed a big part in yield reduction, but since they are MACS I bet he had to hit them pretty hard. I did find a 2008 Belgian study which showed no yield reduction using wettable sulfur, using varieties of only moderate scab susceptibility. if anyone can site some other resources, I'd love to read them. What we are likely to find here is a sea of conflicting reports, I think due to so many variables. I am inclined to think alot has to do with application rates, catalysts and the like. Despite good intentions, many of us growers wind up using a hit or miss strategy that could mean an overapplication, an unfortunate spray overlap (did I wait long enough after spraying that oil), and what not. Being scientific in our approach, like using real controls or siting studies that do so may help. Careful attention to application rates is another, knowing that not just things like lime sulfur can cause a reduction in yield, so can excess oil applications and even hormones. I ABSOLUTELY think that we should continue using anecnotal info, I will, but we also need to share where to find some hard core info. Even though the internet/www has made finding information easier, I have reason to believe finding cutting edge scientific information is fairly difficult for the general public. i will pursue this logic in a more appropriate thread.

Steve Gougeon 52 days ago
ActivityRank: 98

I have not used lime-sulfur in in my orchard because of worries surrounding its toxicity and its effect on fruit and foliage. I do use plain sulfur as my primary fungicide and have reasonable control depending on the year and my spray timing. I sprayed three times at rates ranging from 6 to 8lbs per acre of micronized sulfur. I question the sulfur connection with the "red spot disease" that Michael refers to. The red dots are something I have seen on unsprayed Golden Delicious trees in this area, including trees at a friends house that were loaded with fruit this year, as well as with red dots. I only have a few years with this orchard, but like Brian, I am not seeing any abnormal yield differences between our scab-resistant cultivars and our sulfur-sprayed cultivars. I'm not trying to be a sulfur cheerleader, it has helped me to establish a base line for my orchard of what my input needs to be. Even at these low spray rates I am still doing research on more holistic altenatives.

Michael, I also wonder in Chuck Souther's orchard, you mention that the only changes he made was the sulfur. Wouldn't there have been changes with types of fertilizers too, maybe herbicides. These things would clearly have an effect on yield as well as hand thinning technique. It would be interesting to have a bigger picture.

Michelle (and Chris) McColl 52 days ago
ActivityRank: 73

Our observations tend to support the line being put by Brian and Todd above. While lime sulphur appears highly phytotoxic and certainly reduces yields, we haven’t seen any evidence that wettable sulphur causes yield reduction.

We have heard it said that Cox’s Orange Pippin is highly sensitive to “sulphur”. We have one row of Cox’s that is 200 metres long, with a 10 metre break at the half way mark. The northern half has had no fungicide sprays for the past two years, and previous to that only minimal drift from the adjacent Gala row. The southern half has had 10 to 12 sprays of wettable sulphur in both the 2008/09 season and the 2009/10 season. Standing at the mid point now, there is no discernable difference in the foliage or crop load north or south (and interestingly, the fruit on the northern ie.unsprayed half is almost scab-free). In previous years the northern half had far lower yields (and inferior quality) compared to the southern half due to scab.
We have never sprayed Cox’s with lime sulphur.
Cox’s Orange Pippin may be highly sensitive to lime sulphur, but in our experience it is not sensitive to wettable sulphur.

We also want to get away from spraying copper hydroxide, wettable sulphur and lime sulphur. Two years ago we stopped spraying 25% (or 2 hectares) of our production area. Our arboretum, containing about 80 varieties, has not been sprayed for seven or eight years. It appears (in our environment) after a period of time it is possible to grow most varieties virtually scab-free without any spraying. The question is whether or not you can stay financially viable while the orchard ecosystem is establishing the new equilibrium.

Concerning yield reduction, we have found that there has been an increased tendency toward biennial bearing at our Kalangadoo orchard since converting to organic. This has resulted in very low yields in the “off” year. Our other orchard at OB Flat has not fallen into a biennial bearing pattern and has maintained yields similar to when it was managed conventionally.

David Doncaster 51 days ago
ActivityRank: 32

Michelle and Chris , I'm assuming you have more experience then I so what I say here may not pertain to you. I 've had the orchard for six years now, went organic after my first year . Your last comment brings up a question . How has your thinning gone at Kalangadoo ? Before going organic the spartan block would yield 8-10 bins . in my third year I had 12 . The next two, 17-20 . 2009 saw us with three bins . I can't compete yet with the big growers around here but I found a good market for the smaller apples so I didn't go hard on the thinning . It seems I may have forced my trees in to biennial production . I've used lime sulphur my third year for thinning and very limited micronized sulphur for scab the year after .

[Editor's Note: We now have an entire Organic Thinning category to discuss specific thinning techniques.]

Michael Phillips 50 days ago
ActivityRank: 396

Any acreage within an IPM operation typically achieves organic certification through “conventional organic” techniques where substitution of acceptable spray materials forms the heart of the method. Chuck Souther is a cutting edge IPM grower – he’s one who pushes good boundaries on the chemical front by taking into account ecosystem dynamics to some extent. Herbicides are not a factor: all his free-standing trees stand in a mixed understory. Soluble chemical fertilization may well be though this is a grower who knows nitrates work against good flavor (as well as set the stage for disease). Chuck principally utilized a “wettable sulfur as protectant” strategy before every anticipated wetting event (rate details of which I will post when I hear back from him). The yield reduction at Apple Hill between the organic and IPM block is primarily due to heavy use of sulfur as compared to conventional fungicides. New Zealand growers talk about this as do the Europeans. It’s fair to say we shouldn’t expect as high of yields compared to IPM as nutrient-dense fruit will always be more compact.

Dave Rosenberger in New York reported this in a 2007 edition of Scaffolds (Vol. 16, #1) :
The yield-depressing effects of sulfur and lime sulfur sprays are well documented and have major economic implications for organic production systems that require repeated use of these fungicides… Holb et al. (2003) ran a two-year trial with Jonagold and Boskoop apples in Holland and found that yields in plots receiving conventional fungicides were 33 and 39% higher, respectively, than yields in comparable plots receiving full-season treatments of wettable sulfur or LLS. In addition to the yield loss, the latter two treatments also reduced the percentage of top-grade fruit by 10–15% compared with conventional fungicides. In a non-replicated trial that we conducted at the Hudson Valley Lab last summer, an organic spray program consisting mostly of sulfur, LLS, and Surround (for insect control) reduced yield of 15 cultivars in our test planting by an average of about 50% compared with comparable trees receiving standard fungicides. In all of these tests, yield differences were attributable solely to fungicide effects because all plots received the same fertilizer and herbicide regimes.

This has far less meaning for those of us who understand the “scab dance” and all I refer to when I talk about minimal sulfur in The Apple Grower. Ahh those gray areas between black and white! Steve’s observations are great but based on the fact that his sulfur sprays were kept under 4 applications. Brian’s numbers reflect a soil vibrancy and tree maturity we don’t all have in place yet. Maybe minimal sulfur is called for even in a “pure holistic program” in some years on certain varieties… precisely what I’m currently attempting to investigate. A good orchardist doesn’t rigidly adhere to “either or” as much as juggle weather reality in favor of biological advantage as much as holistically possible. The big negative about sulfur remains the fact that most of you are not getting righteous scab control… and in my opinion that’s because the beneficial flora and fauna in both the soil and tree canopy (leaf surface) are being compromised.

Michael Phillips 47 days ago
ActivityRank: 396

Getting back on the details of Chuck Souther's program in his organic block:

I did not use Lime sulfur on a regular basis other than as a post harvest tool to try and reduce overwintering scab. We have had a problem in the whole orchard in recent years with fire blight so the use of copper hydroxide (Champ for fire blight 12 lb.per acre.) has been the norm in early spring on all susceptible varieties. In the organic block I felt it was wise to start a scab program early anyhow because of the high PAD. The rest of the scab program was based around sulfur, (nu farm microsulf 6- 12 lb.. per acre). In 2009 I made 12 applications. Given the recent years' rainy spring and summers it seemed all I did was spray the organic block. Even the kids that we have work for us were asking "what gives with the organic block and spraying?" In the end, this years crop was dismal at best and we had a nearly perfect 750 foot radius circle of scab problems in the rest of the orchard. Here I worked hard to meet the set backs to "protect" the organic block from the IPM block and in the end the opposite was true, I needed a bigger set back to protect the IPM block from the organic block.

A threshold of four micronized sulfur sprays compromises beneficial organisms plenty, methinks. This is that "grey area" between no sulfur use and fungal fears in preemptive mode. Yield and return bloom may still well be affected even with minimal sulfur but on disease-prone varieties that moderate touch straddles the line between acceptable scab control and wanton disease. Yet even this baseline can be improved upon... noting that everything we do in the orchard ecosystem has ramifications!

alex 39 days ago
ActivityRank:

It is great to see this forum come to life. I have limited experience having been orcharding for only three years. Last year my yields were down to about 10% of the previous year. There may have been some biennialism involved but I also feel that lime sulphur had a role to play - fruit quality was good. This year I applied one lime sulphur early season and then wettable sulphur at 240g/100l (2000l/ha) before rain events during the Mills period (using an air blast sprayer). To this I added 2-3l seaweed extract. I also used a little early season copper but very little as traditional use has generated levels I don't want to add to. Later in the season about 3 weeks after flowering (I have a number of varieties and only one spray program so this is an approximation) I shifted over to Stylet oil to control PM. I used 14l/ha (spraying at a reduced rate of 1200l/ha). In all I have logged 15 spray events. Despite this (it has been a tough year rain wise) my mainstream varieties look terrible black spot wise although the trees look the better for my abstinence from lime sulphur - I am in NZ and so approaching harvest. I also did some trials with potassium bicarbonate and potassium soaps on .3ha of Cox's. My impression at this stage is that altough these have not adequately controlled BS the mix has performed better that the Suphur - but that may be a varietal thing. I find it very difficult to justify 15 spary events if it does not deliver. I am dedicated to the "organic" route but am aware that 6 targeted conventional sprays achieved near 100% BS and PM control in my first year - low initial inoculum levels may have been helpful. Next year?

gkoehler 5 days ago
ActivityRank: 8

This may belong in different heading, but as always, things are inter-related. The less scab the better and as per discussion above, getting that with less suflur is better still. Orchard sanitation is key to getting better results with less sulfur. Shredding the fallen leaves in fall or spring reduces the population of ascospores available to cause new infections next spring. No fungicide application is perfect. By reducing the number of ascospores the number that sneak through preventive spray residue is reduced.

Reduced first generation ascospore infections leads to reduced source points for secondary infections caused by conidial spores. It's all a numbers and percentage game. Fewer leaves = fewer spores = fewer infections.

Bill MacHardy's work has shown that reducing the foundation population in overwintered leaves leads to lower scab pressure. Lime or compost on top of fallen leaves will help too, but takes a lot of material to haul around.

Shredding leaves has it's own difficulties (like when they don't fall until snow is already on the ground). Bill's latest work shows benefit of postharvest urea application to leaves while still on the tree - Chan and Schupp found no negative impact on winter hardiness. Would be interesting to see if same benefit could be realized from an organic nitrogen source in place of urea.

Sanitation first and forever! Open pruning helps too. Sulfur or any other treatment second. - Glen Koehler

[Editor's note: Absolutely! Now could someone start a "Fall Sanitation" thread to continue with comments on this great subject? Thanks.]

russell 5 days ago
ActivityRank: 84

It is said to be impossible to pick up the leaves on ten acres, but we found it possible using a large zero turn mower with a mulcher/bagger in the autumn. The leaves are composted 100% over two years (along with a bunch of other yummy stuff) and then returned to the orchard. While in-place mulching or spraying are helpful, removing the leaves and prunings altogether seems hygienic. I should add that rubbing the bark with strong gloves or gloves wrapped in burlap is actually quite meditative and it doesn't take as long as you'd think at first glance. Not sure if "petting" the trees is a scientific horticultural technique but they seem to like it and you'd think that smoother bark would harbor less spores alltogether.

[Editor's note: Still thinking 'bout that fall sanitation thread. . . ]