John C. Schmid: Scientific Breakthrough, Fire Blight

Another piece from my occasional contributor and retired Ohio State researcher, John Schmid:

One of the first things I learned when I became a technician in the Horticulture Department was just how devastating fire blight can be to apple trees and apple orchards. In the following years I tried to learn as much as was known about the disease.

I learned bacteria that are normally found in orchards cause fire blight. The bacteria can enter a tree through the pollen tube of an open flower during bloom, at the tips of growing shoots, through wounds such as from hail or careless mowing, or less likely, by bark beetles boring into the trunk.

Cultivars and rootstocks differ in their susceptibility. 'Jonathan', 'Rome', and 'McIntosh' are very susceptible to fire blight, while 'Delicious' and 'Golden Delicious' are very resistant. Susceptible rootstocks, such as M.9 are vulnerable to fire blight strikes to root suckers. This can leave you in the unenviable situation of having the cultivar untouched by disease; but with the roots, killed by the bacteria, the tree dies.

Yet, much remained unknown. Antibiotic sprays seemed of some help in preventing outbreaks, but were expensive and had to be applied multiple times during the spring. They also had to be applied every year because no one could predict when infections were likely and they proved to be of little use after an outbreak started.

Young orchards, in their third or fourth year were often struck when just coming into production. The grower is left with no income to offset the cost of establishing, training, and maintaining the orchard through the early years.

Twice in my years at Wooster, southern Ohio growers lost their apple crops to a late spring frost or freeze. We sympathized with them even more as the next year brought horrendous outbreaks of fire blight. It was just one thing after another for those unlucky growers.

Skip ahead a few years. Dr. Ferree and his graduate student, James Schupp (now Dr. Schupp at Penn State U.), and I decided to stop by the small orchard where Jim had his research. The experiment was in its third year and involved taking physiological measurement on 'Golden Delicious' trees that carried differing crop loads. The treatments included the extremes; no thinning at all on one end and no crop, achieved by complete flower removal on the other. These treatments had been applied to the same trees for three consecutive years.

We had just gotten out of the car when we noticed that trees scattered throughout the orchard were dead, all the foliage was brown and still clinging to the branches, a sure sign of fire blight. Incredibly, the trees around them were completely untouched. We were shocked, the trees were all 'Golden Delicious'; it was rare to even see a small fire blight strike on a 'Golden Delicious' tree.

Jim quickly checked his treatment map. All of the dead trees were of one treatment; complete flower removal.

The thunderbolt hit! Everything clicked into place. Discussing it later, it was the same for all of us. I honestly can't say who mentioned what or when, but here is what we all knew in an instant and quickly discussed among ourselves.

Removing a crop for three consecutive years caused a build up of carbohydrates in the tree with no place to go. Excess carbohydrates are normally stored in the roots, but the storage capacity of the roots had been overwhelmed. I had assisted Jim in collecting data on this experiment in previous years. We had already noticed that the leaves of this treatment were much thicker, almost leathery. He had documented the increased dry weight. Now we knew the excessive carbohydrate levels throughout the tree was providing a wonderful growth medium for the fire blight bacteria. Much like diabetes in humans causes an increased risk of infection.

Young trees in their early years, growing fast without a crop would also have an increased carbohydrate level and account for their susceptibility to fire blight.

The southern Ohio crop loss to a late frost or freeze sets up the next spring's fire blight outbreak in the same way.

James Schupp in the next few weeks prepared a "note" for the Journal of the American Horticulture Society. The rest of the summer he did further research for a full paper on the subject in addition to finishing his work on the original project. The most memorable aspect of this study to me was the electron microscope photo of a cell so full of carbohydrate inclusion bodies that the cell wall had ruptured, death for the cell and a sure feast for bacteria.

This was truly a scientific breakthrough, one of the few that I saw in all my years in research. A quote by Louis Pasteur seems to be appropriate at this time: "Chance favors the prepared mind". Like many scientific breakthroughs, this was a case of pure serendipity; it was not what we set out to discover. It truly was a "bolt out of the blue",a true scientific breakthrough.

I worked with fire blight on my M.S. thesis, but in a realtively obscure context: blackberries. I'm the proud author of roughly a quarter of the literature on the fire blight in brambles (much more if you count the thesis). On apples, and pears, however, it's a major problem, and this discovery marked a significant step towards understanding the factors influencing resistance.

John Schmid: AL800, The Rootstock that Wouldn't Root

John Schmid sent another me contribution me another piece a while back, and I keep forgetting to post it. For those who don't recall, John recently retired from Ohio State, where he spent many years as part of that university's well-respected apple breeding program. This time, he recounts a promising rootstock that didn't quite pan out:

In the early 1900s Arnold Lynd of Pataskala, near Columbus, Ohio planted an apple orchard on seedling rootstock. The Lynds noticed after a few years, that a tree on the corner of the orchard was smaller. In fact, that tree eventually became the “family tree.” Its location and smaller size made it easy for the children to pick.

When the time came to replace the orchard, the “family tree” was spared and a new orchard on a modern clonal rootstock was planted around it. This orchard renewal process was repeated once more several decades later with the family tree again spared. When the third orchard was due to be replaced, it was clear that the tree had finally reached the end of the line.

The Lynds (the next generation now in charge) felt that since the tree had survived so long and remained less that half sized, it might have value as a rootstock. Before the orchard was removed, root suckers were collected and grafted onto MM.106 rootstocks to maintain the genetics of the rootstock.

The Lynds delivered these trees into our hands to evaluate the potential for use as a rootstock. Before we could do that, we had to develop roots on the top section of the grafted trees. The potential rootstock was given the name AL800 (AL for Arnold Lynd, 800 for the tree number in his orchard.)

At that time, we had an extensive nursery operation at Wooster. We planted the trees deep with the graft union at the soil line in our stool bed area. During the season, we pegged shoots to the ground and mounded them with sawdust. All other rootstocks that we had in our stool beds would root into the sawdust and provide us with rootstock liners for our nursery, AL800 did not.

In the following years, we tried girdling with wire, wounding, different rooting hormones in different strengths, and even air layering with no success. No scheme was too wild for us to try! A legend grew up around our rootstock that wouldn’t grow roots.

Dr. Ray Miller arrived several years after we’d given up the effort. He established a tissue culture lab and the problem was turned over to him. After a year or so, the word came that he’d been able to develop tiny plants in tissue culture, but no roots. Another year passed and we were told that after a lot of trial and error, and with a lot of manipulations of different hormones in the growth media, success was finally at hand.

AL800 liners finally were produced for our nursery and a replicated rootstock trial was started. AL800 turned out to be dwarfing, roughly the size of the same cultivar on M.26. Apple cultivars on this rootstock, however, proved to be late coming into bearing. Worse, of all the rootstocks in the study, AL800 ranked last in cumulative yield over the course of the trial. This was the end of the AL800 story.

One of the perks of my job was occasionally receiving an excess plant or tree that was not needed in a new planting. I’ll be removing such a tree from my home orchard next year. It is original ‘Gala’ on AL800.

John Schmid: The Hunt for an Improved Melrose, pt. 2

And now the exciting conclusion...

When full production began in our special orchard at Jackson, it soon became clear that no tree stood out as being as superior as the russetted trees were bad. We had to depend on statistics and the computer to choose selections.

Each year yield records were recorded and a 10 fruit sample from each tree was brought to Wooster for evaluation. We were looking for better color, but any improvement would be welcomed, so the data we collected was average fruit weight, length/width ratio, color intensity, percent color, firmness, soluble solids (sweetness), and since russet was a problem some years, a russet rating. Over the next five years, this fruit evaluation made up a large part of my winter’s work.

When the evaluation was over, we made eight selections based on computer analysis that scored better than the standard ‘Melrose’ in color, percent color, and yield. We found no selection that was superior to the standard in any other measurement.

During the years of this study other, better coloring strains of ‘Melrose’ had been identified in France and England. We obtained trees of each and had grown them in our orchards at Wooster.

A commercial grower in Ohio found a sport of ‘Melrose’ in his orchard that seemed to be a spur type. We were able to obtain bud wood and propagate trees of this strain. (A “spur type” has shorter internodal lengths, thus having the advantage of growing more fruit in a given space.)

At this point we were ready for a replicated trial. We propagated our eight selections, the two from France, the three from England, our Ohio spur type, and standard ‘Melrose’ as the control. An orchard was planted at Wooster consisting of six trees of each.

Once more yield records were taken each year. Again 10 fruit samples were taken and data collected. After ten years and six years of fruit data the experiment was finished and all data was submitted to computer analysis. The summer of 2000 was my chance to announce the results to the world, well, to the Ohio fruit growers that attended the Horticulture field day at Wooster, Ohio.

Some of our eight selections were slightly better in color than standard ‘Melrose’, but not as good as the French strains, ‘Melrouge’ and ‘Melred’. In all other measurements, none of the selections or strains was better than the standard.

If you plant ‘Melrouge’ or ‘Melred’, you will get a slightly better colored ‘Melrose’ in most years. Sorry, just an incremental improvement; no real scientific breakthrough here.

The spur type? Well, it turned out to be a true spur type. Want to plant it? I wouldn’t recommend it. The spur type averaged less than one apple a year per tree in our trial.

. . . so much for nearly 25 years of research. I use this as an object lesson for why there are fewer and fewer tree fruit breeding programs at our state universities. You are not guaranteed success, no matter how much time, effort, and resources you bring to the program.

When it was first introduced, there was great hope for mutation breeding. Lots and lots of cuttings, budwood, and seedlings got irradiated, dipped in mutagens, etc. In the end there was comparatively little to show for it. There were a few success stories (the self-compatible sweet cherry, for example, as well as some growth habit mutants in tree fruit), but for the most part the mutants it generated were of limited utility. And when you think of it, it's not that surprising. Mutation breeding is a little like trying to fix a watch by hitting it with a hammer. Much of the time, it'll just break completely. Some of the time it'll keep running, but not as well as before. And sometimes, very, very rarely, there is a tiny chance that it might actually work better. Breaking chromosomes is no different.

That said, given the track record of natural mutant sports in apple, fruit color is probably as good a target for mutagenesis as any trait, since single locus mutations can clearly have a profound effect on fruit color.

John Schmid: The Hunt for an Improved Melrose, pt. 1

I'm pleased to present another contribution from John Schmid, a veteran of many years in the apple program at Ohio State, in an era when public fruit breeding programs were more plentiful and better funded. It's a bit longish, and he's kindly divided it in half, so I'm going to post part one now, and part two later this week, I think:

I had just started work at the OARDC when a project was launched to find or develop an improved ‘Melrose’ apple. About 25 years later, I was given the honor of presenting the results of this project at the Horticulture Field Day in Wooster.

In the late 70’s, the Ohio government had just proclaimed ‘Melrose’ the state apple. The researchers and apple growers in Ohio knew that unlike several popular cultivars, ‘Melrose’ was a high quality apple and well adapted to Ohio, They decided that every effort should be made to ensure that ‘Melrose’ would become popular. As I stated in my earlier post, appearance is the weakness of ‘Melrose’, so the project was to find or create a better-colored ‘Melrose’.

Years earlier, red sports of ‘Delicious’ started to show up in Washington commercial orchards in great numbers. It was suspected, but to my knowledge never proven, that the scion wood used to propagate those trees was somehow exposed to radiation. So in 1977, the Ohio team set out to duplicate this accident with ‘Melrose’.

Large amounts of scion wood was collected and sent to the Ohio State University Hospital in Columbus where the wood was exposed to radiation. Calls to radiation experts found that no one had a guide for how much radiation was necessary, so the scion wood was divided into three lots and exposed at a best guess rate and rates to either side of it.

One thousand rootstocks were purchased and a crew of grafters was recruited (technicians and grad students who couldn’t find an excuse). During the grafting, it was noted that the scion wood seemed to be dry.

That spring, very few grafts “took” after being planted out in the nursery. More calls to more radiation experts suggested that we were off by a factor of 10. Instead of “shaking up the genes” in an effort to find a beneficial mutation, we had fried the graft tissue.

In the nursery, the few grafts that took were flagged and the graft-less rootstocks were maintained to one shoot for the rest of the year. That fall, bud wood was collected and exposed to lower rates of radiation than before. Surviving rootstocks were double budded where possible to ensure the most viable trees for testing. Each bud could be THE ONE.

After a year’s growth in the nursery, the new trees were dug and planted out at OARDC’s branch in Jackson, Ohio. Where there were two buds growing, both were allowed to remain. In all, there were just over two hundred trees under study. Manpower always being at a premium at branch stations, the trees were sprayed, but not pruned beyond what was necessary to get tractors through the aisles.

As the first fruit appeared in this special orchard, it became evident that we’d indeed “shaken up the genes”. A couple of trees had only a few apples, but those it had were 100% russetted. Another had fruit that was not only 100% ressetted, but also had knobs or lobes like a potato! Much conversation was generated after we exhibited these samples. A contest of sorts ensued to name these “sports”. Many names were suggested, but since Dr. Ferree was heading the effort, the one that I liked best was ‘Ferree’s Seek Much Further’. We were undaunted by the levity, if the genes could be shaken to produce such a monstrosity, surly they had been shaken to produce a better ‘Melrose’ as well.

The 'Melrose' apple was developed by Ohio State, and much effort has been made to encourage its adoption, with mixed results. It is, however, an unarguably better apple than much of what is bought today. I wonder if the lack of good red color would have been as much of an issue today, when there are "red" fruited cultivars like 'Fuji', which not only is consistently poorly colored, but which often has a sort of a greenish-brown cast which to me suggests a poorly ripened fruit. (That said, a good 'Fuji' is a wonderful apple...color really has very little bearing on eating quality).

Oh, and for those who don't recognize get it, 'Ferree's Seek Much Further' is a play on 'Westfield Seek No Further', a very nice antique dessert apple with one of the cooler fruit names out there. (There's an apple named 'Slacken Your Belt' or something to that effect that I read about a while ago, and I haven't had any luck tracking any information down about it. That's got to be right up there for the all-time best name. If any one knows anything about it, drop me a line).

Anyway, more to come on 'Melrose' and the perils of mutation breeding. Stay tuned!

John Schmid: Thoughts on apple cultivars

John Schmid sent the following to me a long while ago, before some long-forgotten crisis intervened and I forgot about the blog for an age or two. John has a long career in fruit, having worked for Dave Ferree at Ohio State for nearly three decades, and I'm pleased to have him as both a reader and now contributor. He brings up some good points, to which I have no easy answer:

I was fairly new as a horticulture technician in the late 70's when I had my first encounter with a new apple cultivar called Gala. Up to that time, my favorite apples tended to be 'McIntosh' types. In fact, some of my colleagues thought that the stork had been blown off course; I should have been born in New England.

I was impressed with 'Gala'. Here was an apple that was sweet, but had real flavor. Others in both the research and grower communities were also impressed. The only thing not in favor of the cultivar was its color.

Well-positioned fruit of the original 'Gala' would have a red blush on the exposed side, but vast majority of the fruit on a tree were basically yellow with an orange stripe. So, in those early years the hunt was on for a sport that would produce a better-colored 'Gala'.

As this process was going on, I reflected on the situation. Here we have a superior apple and it has a very unique appearance -- what else could we ask for?

Businesses that manufacture goods go to great lengths to differentiate their products. Remember tail fins on cars? Or hood ornaments? Or logos on pockets? The point is not to make the product better, but to identify one's product in the mind of the customer.

We have that difference built in -- and we want to get a red sport of 'Gala' so it can look like every other apple? It just didn't make sense to me.

In later years, I came to realize that people buying fruit in the supermarket will buy apples based on their appearance, Only a small percentage of shoppers really know one cultivar from another. Thus it is necessary to have a uniformly colored fruit, or it will rot on the shelves.

This fact has also been a problem for 'Melrose', the state apple of Ohio. 'Melrose' is a large blocky apple that has a muddy dark red color over 50-70% of its surface. It is a wonderful multipurpose apple. It has a bright tangy taste, cooks well, and is a good addition to cider. Many people feel that it is the best cultivar for making applesauce.

I have often given people a 'Melrose' to taste. The first response is always, without an exception: "Where can I buy them?" In the supermarket, they don't sell because of their appearance.

What can be done?

The problem really boils down to education. If shoppers could be educated about a cultivar, such as Gala or Melrose; they would want to buy it no matter what it looked like. In fact, a unique appearance would be the advantage I presumed it to be way back in the 70's.

Growers can and do educate their customers at their roadside markets, but that is a very small segment of the market. The effort has to be mass-market advertising to make much of a difference.

I even mentally designed an add campaign for 'Melrose' along the line of: "Yes it's ugly, but boy it tastes good." My inspiration was the old Volkswagen ads for the Beetle that tapped into the love of the underdog in the American people.

Yes, advertising campaigns can be created, but the overriding problem is that there is no money for such an ad campaign. The growers are barely surviving now with international competition. Supermarkets will sell what the customer buys and the customers will buy what the supermarkets have to sell. There seems to be no incentive for anyone who could afford to advertise, to invest the kind of money necessary to promote superior apples. So, many good cultivars come and go without a chance to reach the buying public.

Does anyone have a solution? Comments?

I know I've harped on this before, but why, with all the zillions of cultivars out there (a 1905 publication reported 17,000 apple cultivars) did we wind up with the same 4-7 in every store in every state? And while some are pretty decent (a truly ripe 'Fuji' is a wonderful experience), in general they hardly represent the very best there is out there. With some fruit, there's a barrier in the sense that no one is paying attention to the cultivar name (which is virtually never even available). People go to the store to buy, for example, a peach, not, say, a 'White River' peach. No one wants to be surprised, so there's a certain homogenization that's only natural. But if there was one fruit that could overcome that hurdle, it's apples. People know apple cultivars. Granted, just a handful, but people are aware of the fact there are differences in apple varieties, and they're aware that there are particular ones they like. That's an opportunity to build a market that's not being taken advantage of, or at least not very often. Certainly there have been additions to the elite club that is supermarket apples over the past decade ('Pink Lady', for example) but they are few and far between. As John mentions, American apple growers are taking a beating from international competition. Why not take advantage of the fact that America is home to more apple cultivars than any place on earth, all developed and adapted for conditions here, and build markets for some of the other often forgotten apples. There's been such an effort, on a rather localized basis, with the 'Gravenstein' apple in the Sebestapol area in California. There are literally hundreds of apples worthy of similar campaigns.

I could ramble like this for another page or two, but like I said, I don't know what the solution is either. But the opportunity is there if some one does.