Know Your Fruit Tree Rootstocks

Whether you are bare root fruit tree shopping in winter or picking out containerized fruit trees in other times of the year, read the label on the tree. Both of them.

After you're done salivating over the fruit's juicy details after reading the top tag, pay attention to that bottom label.

That tag, the rootstock information, is critical in determining whether the tree will live or die in your soil.

Fruit trees are grafted onto various rootstocks to extend the range for that tree, giving it the ability to grow where it might not normally be possible (due to sandy soils, wet soils, crown rots, nematodes, etc.). Rootstocks can also help control the height of the tree or offer drought tolerance or more protection in cold winter areas.

But no single root stock is perfect. Each has its pros and cons.

Here is a list of some of the more commonly available rootstocks for deciduous fruit trees, along with their pros and cons, according to wholesale fruit tree grower, Dave Wilson Nursery:

Nemaguard  peach seedling

    

Pros root-knot nematode resistant, vigorous, strong tree.

Cons susceptible to root-lesion nematode, prefers sandy soil, susceptible to oak root fungus; bacterial canker, prunes on this rootstock are subject to brown line

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Lovell peach seedling

     

Pros slightly more resistant to wet conditions than Nemaguard but prefers well-drained soils, slightly more resistant to bacterial canker than Nemaguard.

  

Cons susceptible to root-knot and root-lesion nematode and to oak-root fungus, some what susceptible to bacterial canker, prunes on this rootstock are subject to brown line.

 

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Citation  interspecific peach plum-rooted cutting

Pros highly compatible with apricot and plum, induces early bearing, tolerant of wet soil conditions, resists root knot nematode, advances maturity and increases size and sugar content of fruit.

Cons susceptible to crown gall, bacterial canker and oak root fungus, intolerant of virus with peach or nectarine.

 

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Viking interspecific peach, almond, plum; apricot-rooted cutting (patented)

    

Pros vigorous, root-knot nematode resistance similar to Nemaguard, productive, precocious tree, increases fruit size, considered well anchored, less susceptible to bacterial canker than seedling rootstocks, tolerant of wet soil conditions, tolerant of saline and alkaline soil conditions.

Cons Trees on peach x almond hybrid rootstocks, including interspecifics, are very sensitive to dehydration. While planting, keep roots damp. Irrigate after planting.

 

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Atlas interspecific (patented) peach, almond, plum; apricot-rooted cutting

Pros extremely vigorous, root-knot nematode resistance similar to Nemaguard, productive, increases fruit size, considered well anchored, tolerant of saline and alkaline soil conditions.

    

Cons delays fruit maturity in some varieties, intolerant of wet soil conditions, intolerant of dehydration in transplanting.

 

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Titan Hybrid Titan almond x Nemaguard peach hybrid seedling

    

Pros extremely vigorous, may have root-knot nematode resistance, considered well anchored, tolerant of calcareous soil conditions.

Cons trees may be excessively vigorous on good soil, may delay maturity of fruit, more susceptible to crown rot than peach seedling rootstocks, intolerant of wet soil conditions.

 

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Myrobalan 29-C plum-rooted cutting

Pros makes large tree, immune to root-knot nematode, tolerates wet soils, less sucker development than Marianna 2624.

Cons tends to lean, some incompatibility with almonds, prunes subject to brown line on this rootstock, may set lighter crop than Marianna 2624, susceptible to oak root fungus.

 

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Marianna 2624 plum-rooted cutting

     

Pros slightly dwarfing, moderately resistant to Phytophthora crown and root rot and oak root fungus, tolerates wet soils, root-knot nematode resistant.

Cons tends to lean; shallow roots the first few years, very susceptible to bacterial canker, incompatible with peaches, nectarines and some almond varieties, suckers profusely, susceptible to crown gall, almonds subject to brown line disease and union mild etch.

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Mazzard  cherry seedling

Pros more water tolerant than Mahaleb, cold hardy, resists root-knot nematode, vigorous, moderately resistant to oak root fungus.

Cons slow to bear, large tree prone to root suckering, susceptible to crown gall, bacterial canker; root-lesion nematode, scion doesn't show buckskin infection as quickly as on Mahaleb.

 

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Mahaleb cherry seedling

Pros more drought tolerant than Mazzard, resists bacterial canker, smaller tree than Mazzard, moderately resistant to crown gall and root-lesion nematode, shows buckskin infection quickly.

Cons intolerant of wet heavy soils, attracts gophers, tends to sucker, susceptible to oak root fungus, some root-knot nematode susceptibility - very susceptible to Phytophthora crown and root rot and Prunus stem pitting.

 

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Colt (patented) cherry rooted cutting

Pros tolerates wet heavy soils better than Mahaleb, resists bacterial canker; cherries on Colt are field resistant to cherry stem pitting.

Cons drought sensitive, slight to not dwarfing under California irrigated conditions, susceptible to crown gall, not cold hardy (not a problem in California).

 

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M 9 apple layered cutting

Pros dwarfs to 40-45% seedling size, very precocious and productive, increases fruit size, has field resistance to cherry stem pitting disease.

Cons shallow rooted, drought sensitive, trees require support, susceptible to fireblight and wooly apple aphid.

 

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M 26 apple layered cutting

Pros dwarfs to 55-60% seedling size, precocious and productive.

Cons shallow rooted; drought sensitive, staking or trellis usually required, susceptible to Phytophthora, susceptible to fireblight and wooly apple aphid.

 

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M 7 apple layered cutting

Pros dwarfs to 65-70% seedling size, widely adapted to various soil conditions, moderately resistant to Phytophthora.

Cons suckers, staking may be required, susceptible to wooly apple aphid.

 

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M 111  apple layered cutting 

Pros tolerates waterlogging and drought, well-anchored, resists wooly apple aphid, dwarfs to 90% of seedling-rooted size, good for sandy soils.

Cons susceptible to crown rot under very poor conditions.

 

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NCB (Northern California Black) walnut seedling 

    

Pros vigorous, resists Verticillium wilt, oak root fungus and root-knot nematode.

Cons susceptible to Phytophthora crown gall and root-lesion nematode, Persian (English) walnut on Northern California Black subject to black line.

 

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Paradox NCB x Persian walnut hybrid seedling

Pros very vigorous, may induce better quality and productivity. Resists root-lesion nematode and certain Phytophthora species, grows better in heavy, wet or low fertility soils than NCB, resistant to oak root fungus.     

Cons highly susceptible to crown gall, may be less resistant to oak root fungus than Northern California Black, Persian walnuts on Paradox subject to black line.

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Generally, your local, independently-owned nursery will pick the combinations of fruit tree and rootstock that will work best in your area.

Bare Root Fruit Tree Shopping? Buyer Beware!

Mid-winter is bare root fruit tree shopping time here. And who can't resist a bargain? This is the time of year to find truly inexpensive, fruit or nut-bearing trees.

And gardeners on a budget might start their shopping at the big box stores, where many bare root trees are priced under $20.

But beware. 

Unlike local, independent nurseries that tend to stock fruit and nut varieties that perform well in your locale, the box stores get in varieties that may be better off at their sister box store...in the desert.

Case in point:

 

 Last Wednesday, I shopped the nursery section at a local big box store in Elk Grove (Sacramento County, CA) and a locally owned, independent nursery. The bare root fruit trees available at the box store took up about six pallets, approximately 20 trees per pallet, each with their root ball encased in a sealed plastic bag. 

If you read the blog post about choosing and planting bare root fruit trees, you know that examining the roots is an important selection criteria. You're looking for healthy roots! Kinda hard to do that when the roots are in plastic.

There were only 5 peach and nectarine varieties available at the box store: Florida Prince peach, Early Elberta peach, Earli Grande peach, Panamint nectarine and Gold Mine Nectarine.

To the casual shopper, the reaction might be: "Oh boy, peaches and nectarines!"

But to the Sacramento-area gardener who came armed with a copy of the Sunset Western Garden Book or the online catalog of wholesale fruit tree grower Dave Wilson Nursery, the reaction is probably: "These are all low chill varieties, better suited to the desert!"

Yep, it is not unusual for the sales staff at the headquarters for a large chain store to choose fruit tree varieties based on price and appropriateness for the majority of its customers (lots more people down in So Cal). Hence, their selections may include trees better suited for warmer winter areas. Or, someone at big box store headquarters thinks Sacramento is in the desert.

Fruit trees need a certain number of "chill hours" during the winter in order to induce dormancy to allow them to produce well the following spring and summer. A "chill hour" is any hour below 45 degrees, between November and February. 

Here in the Central Valley, 600-800 chill hours are normal. Right now, in late January, the total chill hours for parts of Sacramento County is nearly 900 hours. That total is plenty for most peach and nectarine varieties, including the tastiest ones. 

In Southern California, "chill hours" don't amount to much. Many parts of Los Angeles and Orange County right now have accumulated less than 200 chill hours. So, the only deciduous fruit trees that succeed there are the ones with low-chill requirements.

"Most low chill varieties don't have great taste," says Ed Laivo of wholesale grower Devil Mountain Nursery. "They give up flavor to be a low chill variety."

And sure enough, if you check out the Dave Wilson Nursery fruit taste test results, you won't find any of those big box store peach and nectarine varieties in the Top 10. Or the Top 20. 

The fruit taste tests have been conducted at Dave Wilson Nursery since 1993, with a panel of several dozen taste testers sampling up to 30 fruits at each setting. And they're not just the varieties sold by Dave Wilson Nursery. Over 1600 varieties of fruit have been taste tested over the years.

 The False Allure of Low Prices

The casual gardener shopping at the box store may also note the bare root fruit tree price tag, "$15.99", and be willing to give it a try at that comparatively low amount.

But how happy will that casual gardener be with those selections in a few years, if no one will be pleased with the taste or production?

Down the street at the local nursery, the price for a bare root peach or nectarine tree is approaching $25-30. But at that local nursery, the selection is much better. On the day I was shopping, the local nursery had 22 peach varieties and 16 nectarine varieties! Most, if not all, were trees that would thrive here locally, producing fruit that has scored high in fruit taste tests, including the top winners in Dave Wilson Nursery's overall scorecard: the Arctic Jay white nectarine, Indian Free white peach, Snow Queen white nectarine, O'Henry peach and the Arctic Supreme white peach.

Dave Wilson Nursery Fruit Tasting Results

 
At the local nursery, there was no plastic wrap guarding a root inspection of their bare root fruit and nut trees. As at many local nurseries, the roots of bare root fruit trees are plunged into a moist mix of sawdust and compost. A customer can easily pluck out a tree and examine the roots (you're looking for moist, plump, healthy roots).

Another reason to avoid low-chill requirement fruit trees, if you can: they tend to bloom too early. A fruit or nut tree that blooms too soon (January) in Northern California is asking for a whipping from the rest of the winter storms that come in February and March. The spread of rain-borne disease spores such as brown rot is increased when the blossoms are exposed.

So, when is a bare root fruit tree bargain not a bargain? When it's not the right tree for the right place. 

Whenever shopping for trees, shrubs, annuals or perennials, toting along a copy of the Sunset Western Garden book or calling up a good online reference on your smart phone is good plant insurance.

Bare Root Fruit Trees: Choosing and Planting

What is a bare root fruit tree? A young fruit or nut-bearing deciduous tree, offered for sale in the winter. “A stick with roots”. Fruits include apples, apricots, apriums, cherries, figs, mulberries, peaches, pears, persimmons, plums, pluots, nectarines and pomegranates. Nut varieties are also available bare root in the winter, including walnuts, almonds, pistachios, filberts, chestnuts and pecans. Vine and bush fruits are also for sale in the winter, including blueberries, grapes and kiwi. Citrus is an evergreen plant, available year round.

 

Why grow your own fruit? For better health and better taste. Nothing beats the taste of home grown fruit! What follows are some tips for

turning this...

 Into this!                                                                                                Or this!

 

Shop local. Your local nurseryperson knows your soil and growing conditions, and will carry fruit tree varieties that will do well in your area. Of those, choose fruit trees that you enjoy! Wondering which ones taste the best? Master fruit tasters have their favorites listed online, at davewilson.com, a wholesale grower of fruit and nut trees. Consider getting several trees that will ripen at different times.

Before You Buy, Plan Ahead. Fruit trees do best in a sunny location with good drainage. They need eight or more hours of sun. Six hours of sun is pushing your luck. Wet soils are a major cause of fruit tree failure. 

 

If that hole you dug doesn’t drain within 24 hours, build a raised bed, at least 4’ x 4’x 12-16” high. Cherries and apricots need the best drainage for success. The fruit trees most tolerant of slow-draining soils are apples and pears.

Don’t be too concerned about a crooked top. After you plant a three to five foot tall bare root fruit tree, you can cut it off at knee-height. That way, the fruit-bearing branches will be lower, within easy reach. If you don’t let the tree get taller than seven feet, that fruit will ALWAYS be easy to reach.

Pay attention to the bud union. This is the spot where the tree variety is attached to the rootstock. It should be straight, not bent.

Look at the roots. They should not be brittle, damaged or cracked.

Walk away from bare root trees that:
• Have tunneling around the bud union (they might be borers).
• Oozing, dark colored bark (might be bacterial canker).
• Have been at the nursery for more than two years, if they are in containers. If in doubt, ask the nurseryperson.

When you get the tree home: Treat it nice, immediately. Don’t let the roots dry out. If you are going to plant later that day or the next day, place the tree in a bucket of water or cover with a wet blanket. If it is going to be several days before you plant, bury the roots into soil (“heeling in”). This can be in your garden soil, compost, potting soil, or even a pile of wet leaves.

Dig a $50 Hole for that $20 Tree.
The hole should be wide, not deep. About four feet wide and as deep as the rootstock portion of the tree. Loosen the six feet of surrounding soil outside the hole to that depth. Feeder roots travel outward, not downward.

Plant the Tree Correctly. Set the tree on a slight mound in the middle of the hole, and gently coax the roots to face outward. Look for  a color change on the tree below the bud union; the tree should be planted no deeper than that. Ideally, plant the tree with that mark about an inch above the existing soil line to allow for settling. Set your shovel handle across the hole to determine that point. Use only the soil that came with the hole.

Top With Mulch. After planting, surround the tree with three or four inches of organic mulch; the mulch should extend out several feet. Mulch feeds the soil, suppresses weeds, cools the soil in the summer and helps maintain even moisture, too. Don’t let mulch touch the trunk, though. That can lead to rot problems.

Fertilize? Wait until the tree is actively growing, choosing a fertilizer that lists fruit trees on the label. Whichever fertilizer you use, read and follow label directions.

Add Water. Carefully. The primary cause of fruit tree failure is poor irrigation: either too much or too little water. Use a moisture meter or a soil auger to determine how wet or dry the soil is at root level. Or, grab a handful of the soil at a depth of 8 to 10 inches to determine how wet the soil is. Start doing this when that new fruit tree begins to flower. And, do it before you water.

  

Give the tree some sunburn protection. Paint that bare stick with a 50-50 mix of interior white latex paint and water; or, purchase tree whitewash at a nursery. That new tree is very susceptible to sunburn, which can lead to a cracked trunk…an entry point for insect and disease problems. 

In a few years, with a little bit of care, your kitchen counter will be overflowing with homegrown, healthy fruit.