Freeze damage to tree fruit buds and blossoms

The Front Range is expecting a winter storm with temperatures expected to reach the low 20’s Fahrenheit, 3 to 5 below 0 Celsius. This event will likely cause significant bud and blossom death in fruit trees in this area, as well as to other fruits and vegetables. How much damage is determine by the specific plant (apple, peach, grape, spinach, etc) and the development stage.  There are methods to limit or prevent damage, and we recommend you do some research and apply as appropriate/reasonable to your specific plants, location and resources.  Mark Longstroth with Michigan State University Extension has a couple of tables with critical temperatures for tree fruits, which you can find here:

This weather event is not expected to out right kill any apple trees on the Front Range, but local conditions and the health of individual trees vary, so it is possible.  We will keep an eye on our trees around Boulder County and certainly take note of this event.

Newly planted apple trees in Apple Valley

Twelve newly planted apple trees are now growing in Apple Valley, just west of Lyons, Colorado. A landowner contacted us a few months ago and we agreed on Central Asian apple trees. All are grafted, some last year, some this year, on Antonovka rootstock, and are therefore full sized trees when grown out. A neighboring landowner heard about the project and volunteered to take three trees, for a total of 12.  It was a beautiful day to be outside planting in beautiful Apple Valley, and the family living on the property did a lot of the heavy lifting to get the trees in the ground and are going to take great care of the trees in the coming years.  The land owner also did a lot of the heavy lifting and, key point here, made the property available for some trees.  The neighbors who took the three trees are master gardeners, and their property reflects the skills and effort required.

Apple Valley still has some apple trees, two in the immediate area, but not nearly as many as in the late 1800’s and early 1900’s.  We are hoping to change that, and are well on the way to doing so with this first planting.  There is a bit more room on the property, so we may be helping to get a few more in the new orchard.  Thanks to everyone involved.

Apple Valley Orchard

Apple Valley Orchard Location

Who’s doing what with apple biodiversity?

I thought it would be nice to have a list of projects working to protect apple biodiversity in North America (or elsewhere, if any readers can add information in the comments). Here’s a start:

  • Widespread Malus … that’s us! Working to build a highly diverse collection of Malus sieversii, as well as distribute scions, grafted trees, and seedlings.
  • Apple Diversity Group … a collaboration between Dalhousie University and Agriculture Canada, this group’s Apple Biodiversity Collection in Nova Scotia has 1000+ different apples, including about a hundred Malus sieversii.
  • USDA Plant Genetic Resources Unit … located in Geneva, NY, USDA PGRU maintains one of the world’s most extensive apple collections, including diverse wild apples (M. sieversii, M. orientalis, and others). Interested members of the public may request open-pollinated M. sieversii seed from PGRU.
  • Temperate Orchard Conservancy … located in Oregon, TOC is replicating the Botner Collection (perhaps the largest private collection of apples in the world … 4,500 different apples).
  • Montezuma Orchard Restoration Project … promoting apples and orchards in Montezuma County, Colorado and around the state. Also locating and propagating rare Colorado Heritage apples.
  • North American Fruit Explorers … a group of folks interested in all kinds of fruit. There are quite a few members with their own diverse collections of apples and other fruit. Visit the web site or the facebook page.
  • Seed Savers Exchange … not just for seeds! Iowa-based SSE has quite a nice collection of apples (hundreds), and numerous members who share apple scions with other members.
  • Agrarian Sharing Network … is sharing diverse fruit and vegetable material in the Pacific Northwest. ASN has done extensive evaluations and cloning of the Botner collection and several other large bioregional collections, and is involved in a number of propagation fairs.

Can you help us add more projects to this list? Please send us an email!

The future of the apple

A hundred and fifty years ago, there were thousands of named varieties of apples in North America.  Today, most of them have disappeared.  As pests and diseases evolve, and with the need to adapt to emerging conditions (climate change, anyone?), we need diverse apple genetics more than ever. But, that genetic diversity is threatened.

USDA apple 'core collection' rows at the USDA apple collection in Geneva, NY.

Dr. C. Thomas Chao, USDA apple collection curator, describes the collection to a tour group. USDA has a world-class collection of apples in Geneva, NY, including the group of Malus sieversii individuals we are acquiring. (c) 2015, Eric Johnson

The genome of the domestic apple is derived mostly from a couple of wild species, including in particular Malus sieversii, which is native to Central Asia. As apple seeds were traded and grown westward along the Silk Road, the available pool of genes was narrowed, so that historical European apples carried less overall diversity than their relatives in Central Asia. The apples brought from Europe to North America resulted in further genetic narrowing, although the “Johnny Appleseed” phenomenon of planting randomly cross-pollinated apple seeds did result in a expansion of apple varieties here. Add in industrial agriculture’s focus on a dozen or so types, many of which are closely related to one another, and the picture for the future of the apple production is uncertain.

At the same time, Malus sieversii populations are under pressure in Central Asia, through clearing of forests for development, harvest for firewood, etc.  This has truly disastrous potential, as the entire world is dependent on those forests for new genes to improve domesticated apples.

Fortunately the situation has begun to change. There are projects in Central Asia to protect wild apples, and breeders are working with these wild apples all over the world.

Close to home, USDA personnel and researchers in host countries collected seeds in the 1990s from threatened wild apple populations across Central Asia, in order to propagate the species and conserve genetic diversity. Collection localities ranged from moist, high-latitude sites with extreme winters to dry, lower-latitude hilltops with thin soils and less precipitation than Boulder typically receives. USDA established an orchard of more than a thousand Malus sieversii seedlings at Geneva, New York for use in breeding and research. Phil Forsline, one of the USDA scientists involved in these expeditions, estimates that these expeditions “more than doubled” the available apple biodiversity in North America.

Scientists have also assessed the genetic diversity of these trees and identified “core collections” of individuals that include the great majority of the diversity likely to be found in the M. sieversii orchard in Geneva. As a result, it’s apparent that a carefully-chosen collection of 100 or so individual trees can represent an enormous swath of available worldwide apple biodiversity. Deliberate grafting of multiple genetic individuals on each tree could fit them into a large suburban backyard.

We have used USDA’s Genetic Resources Information Network database to prioritize acquisition of individuals from the highly diverse core collections. With help from apple collector and breeder Don O’Shea of Ogdensburg, NY, who grafted trees for us this year, we now have about 50 of the necessary trees “in the ground” here in Boulder.  We’ll continue to request additional apples from this diverse subset of USDA’s collection in coming years, doing the grafting ourselves now that we have gained the necessary skills.  Eventually, we’ll build out our collection to include as many of the 100+ members of the diversity core collections as possible.

2015 M. sieversii scions on Antonovka

2015 M. sieversii scions on Antonovka rootstock in April, 2015. Starting small! (c) 2015, Eric Johnson

That’s when the real fun begins.

First, we plan to make clonal material from these trees available to others at low or no cost, so that more people can take advantage of and protect this priceless genetic material.

Second, as the trees in our own Malus sieversii orchard begin to bear fruit, we’ll collect seeds and distribute those, making it possible to distribute an entire collection of apple biodiversity, akin to our own, in a single padded mailer, for the cost of a couple dollars of postage.

Third, while I’m sure the wild trees will be lovely, and some will produce useable (if not commercially popular) fruit, we’ll start to make controlled crosses with domestic varieties.  Our goal here will be to begin creating the apple varieties of the future … apples adapted to our local conditions and needs.

Many of the trees at Geneva have shown some resistance to fireblight, perhaps the most significant disease of apple trees in our area. Some of the individuals we plant locally will have a degree of fireblight resistance. We anticipate that some of their offspring will also have fireblight resistance. In the long term, the potential exists to develop disease-resistant varieties, reducing the need for expensive chemical  disease controls.

We’ve actually already begun to distribute these wild apples in a somewhat less-organized way.  As a result of its work being publicized in Michael Pollan’s Botany of Desire, USDA has made open-pollinated M. sieversii seed from its Geneva planting available to the general public. Labeled as to the identity of the mother tree, the pollen parents of these seeds are a mixed bag of whatever M. sieversii pollen the bees happened to be carrying around. We have grown out young trees from these seeds, using seed lots from eight mother trees. We have distributed more than 100 seedlings from the open-pollinated seed lots to interested parties, and have additional seedlings awaiting permanent planting locations.

Diverse assortment of grafted Malus sieversii trees, collected in nursery bed with hail shield, Boulder, CO. (c) 2015, Eric Johnson

Grafted Malus sieversii trees after a season of growth in the nursery, September 2015. Note the hail shield … a worthwhile precaution in our climate. (c) 2015, Eric Johnson

It’s important to note that most of the M. sieversii trees, and their immediate offspring, will not bear fruit marketable for fresh eating. In modern apple breeding programs, thousands of seedlings may be grown out to identify a single new variety for commercial production. However, for local culinary uses and smaller-scale production, a much larger fraction of seedlings may be acceptable.  Others will bear fruit that may be made into preserves, or pressed and used in juice blends, fermented cider or vinegar.  And in the long term, there is great potential for breeding high-quality varieties for fresh eating using a local M. sieversii collection.

Anyone with an apple tree, or enough space for one, can participate in this important work. The future of the apple can be created in our yards and gardens.