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How to Do a Scratch Test on Trees & Plants

by Stark Bro's on 04/29/2014
Scratch Test Tree (Before)

When spring finally arrives, plants and trees start to wake up, and the gardening world gets exciting! It is also the time of year to evaluate what survived the winter. One common misconception this time of year is that all trees and plants wake at the same time. When we compare dormant plants and trees to things that are already waking in our gardens, it’s like comparing apples and oranges.

Today, we’re going to equip you with one of the most handy tools that you can use to determine what’s still living: The Scratch Test.

1. Scratch Test: Fruit Trees

Tree Layers (Including Cambium)The most telltale way to determine if your young dormant trees are still alive is by checking the cambium layer under the bark. The task is simple!

What you need:

  • Your thumbnail or a smooth knife

How to do a scratch test:

  1. With your thumbnail or knife, lightly scratch a small spot into the bark of the tree’s trunk (in a location about halfway up the tree).
  2. Look for wet tissue beneath the bark layer that is scratched back. It should have a greenish hue — this is living tissue.

If you find that the cambium layer beneath the bark has become dry, brittle, and brown, then it indicates that the tree has failed to live.

At Left: living tree; at Right: dead tree [click images to view larger]:

Scratch Test Tree (After) Green Wood  Scratch Test Tree (After) Dead Wood

Sometimes, after performing a scratch test, you may discover the tree’s trunk shows no signs of life even though new growth still sprouts from the roots. This happens in grafted trees if the top-portion (the grafted variety) dies while the rootstock goes on living. If this happens, then it is best to replace the tree. Letting just the rootstock grow will result in a tree that lacks the qualities of the grafted variety you originally chose to plant. Rootstocks are used for characteristics like dwarfing and hardiness, and are often not ideal candidates for fruit-bearing trees.

Things to avoid when performing a scratch test:

  • Do not cut a large wound into the tree to determine whether or not it is living. A small spot will suffice.
    • Large wounds cut into your tree will require more effort to heal over.
  • Do not perform a scratch test on a branch/limb of the tree.
    • Testing the trunk is necessary. Limbs can break/die without determining the status of the rest of the tree.

2. Scratch Test: Berry Plants & Vines

For berry plants and vines, you can still attempt a scratch test to identify the living tissue. Simply follow the steps above for a scratch test on trees, and adjust to accommodate the size of the berry plants’ canes or vines. Pick a spot on the young cane/vine that is a few inches above the soil level to scratch.

Scratch Test Berry Plant (Before)  Scratch Test Berry Plant (After) Green Wood

Many berry plants send new growth up from their roots, so a dead cane may not determine a dead plant; however, a living cane will determine a living plant. With that in mind and, since some plants may feature thorns, you may prefer pruning in order to look for living tissue in your berry plants and fruiting vines.

3. Prune Back: Berry Plants & Vines

What you need:

  • A pair of sharp and clean pruning shears

How to prune to check for living tissue:

  1. With your pruners, cut from the tips of the canes, working your way back toward the ground.
  2. Cut the canes back little by little and check for signs of life after each cut.
  3. Stop cutting back once you reach green, living tissue.

Scratch Test Berry Plant Pruning (Green Wood)You are still looking for greenish, wet, living wood, but it may be necessary to cut dry dead tips back to find it. Cutting this dead wood away also helps the plants to sustain healthy growth during the growing season.

If your berry plant exhibits no living tissue in the canes above the ground, and you are also not seeing any new growth sprout from the root system well into the growing season, then your berry plant is likely no longer living. Replacing the berry plant is recommended in this case. It would also be a good time to assess water drainage, soil nutrients, and soil pH in that location if the cause of death is unknown.

Now that you know how to check to see if your plants and trees are living, it’s also important to know that, if they are still dormant, they simply need more time to break dormancy — especially if this is their first growing season in your yard! Each year, the seasons and the weather are slightly different, but living plants and trees will always wake up when they’re ready.

Remember: dormant berry plants and fruit trees may take anywhere from 4-6 weeks before showing signs of growth after planting.

25 Comments

  1. Mike Obea permalink

    What about checking viability of nut trees? I assume it’s same as fruit.

    • That’s right, it would be the same for just about any young vascular plant/tree. :)

  2. John Zbesko permalink

    I fear I may have lost my strawberries. They are planted in two half oak barrels on a back deck. Winter was bad in the Chicago area. No green leaves are evident in the barrels, even though I notice green strawberry leaves in a nearby community garden. Any quick tests for viability?

    • In the case of strawberries, your best bet would be to go in and manually remove what is dead (it doesn’t benefit anything to leave it there anyway), so you can find what’s living if anything survived.

      The dead plants will be brown and brittle, and even the roots tend to come out of the soil easily. The plants that seem firmly rooted, and plants that have some green/life to them, should be trimmed back. Hopefully you’ll find that not everything was lost to old man winter.

      I have my strawberries planted in an old half-barrel as well, and I had a lot of dieback due to the winter. If I hadn’t placed straw over them for protection this past winter, I’m sure I would have lost more than I did. When I uncovered them this spring, I took my pruners out and clipped out all of the dead stuff, and ended up finding living plants in the process!

      • John Zbesko permalink

        I did remove dead leaves and runners and have examined the crowns. I can’t tell if they are alive, even if they are supple. They’re not green. Never occurred to me last fall that I should have mulched the barrel.

        • Maybe try removing one of the crowns and cut into it, sort of like a cross-section — the idea is to see what’s under the surface to determine what is living. Granted, you don’t want to do this to all of the crowns, but you’ll get an idea of what’s going on with your plants.

  3. LaDonna permalink

    I have a Balaton cherry tree that was planted Fall 2012. I did the scratch test and it is most definitely green. However, it has no leaves or any signs of growth. All the other cherry trees have already bloomed and everything. Should I just replace it?

    • I’m not sure you should replace a living tree just because it’s not keeping up with the rest of the trees around. If your tree was only planted in fall of 2012, it is likely still too young to bloom, and the leaves tend to come during/after the blooming period of the growing season. I’d recommend waiting until there is no life in the tree before you give up on the one you have! Yours may simply need more time.

      I have a persimmon tree that I thought was dead one year even though the scratch test showed me it was alive. I eventually stopped expecting it to leaf out and I was even contemplating what I’d replace it with. Then, almost over night, it had new leaves everywhere! It was kind of like “the watched pot never boils”. :)

  4. Marcus permalink

    Sarah,
    In NW lower MI, I went out several weeks ago to prune out my hobby orchard. I noticed that my Starking plum trees (about 4 yrs old,now) are becoming heavily covered with lichens. Most other trees are not. I have read that lichens are not a detriment to a tree, but it just doesn’t look ‘natural’ to me.

    What say you, and what recos would you have?

    • Lichens may seem like something that needs to be removed, but they’re really harmless. In fact, they tend to form in environments that receive good moisture and sunlight (to help the symbiotic nature of the fungus and algae that create lichens), and you often find them in forests and wooded areas — that sounds pretty natural to me! :)

      However, if you don’t like the lichens on your trees, you can remove the branches they have developed on, but there aren’t really sprays that will control lichen development.

      If lichens are on the trunks of the trees, I wouldn’t recommend trying to remove those. Lichens are usually firmly attached to the sites they are found on, but they tend not to like shaded areas, so as the plum trees mature and develop a nice canopy you may see the lichens naturally decline.

      • Marcus permalink

        Sarah,
        Thanks. You confirmed what others have told me around here. We all live on fully or partially wooded acreage, and most of the trees out in the ‘woods’ have lichens.
        ‘Doubting Thomas’ here just needed an expert’s opinion! I will leave them be! Hopefully will get some fruit this year!

  5. Mark Reid permalink

    I have a muscadine vine that is about 3 years old. It has grown very slow form the start. I noticed all the leaves have holes all in them. I don’t see any bugs on it and I put dolistic lime around it and a little 13 13 13. What could be causing this?

    • Assuming that the holes are just holes and not a fungal issue, slugs and snails could be the culprit. I have that same thing going on in my garden with my new muscadine vine. If you have some egg shells leftover from meals throughout the week, rinse and break them up and sprinkle them along the ground around your vines (and your trellis if your muscadines are growing on one) to work as a snail and slug deterrent.

      In case it is a fungal issue, which many grape vines can be sensitive to, you might want to consider using a fungicide like copper-based bordeaux, which is a natural fungicide so you can use it in organic gardening.

  6. Gary Dreher permalink

    While I don’t have a comment or question about the scratch test, I do have a question about my dwarf peach trees, one Reliance and one Intrepid, which are about 7 to 8 years old now. There are no signs of blossoms on either tree, but leaves are growing well. Should I see blossoms by now? It seems that in previous years by early May the trees were full of flowers.

    • Hi Gary! It depends on where you are located, but most peach trees have finished blooming by this point. This is probably the same for peach trees in your area, especially if you have typically seen peach tree blossoms by this time in previous years.

      After this past relentless winter, with harsh low temperatures, many peach trees have had their sensitive fruit buds damaged. Even a cold-hardy variety’s unopened fruit buds are at risk of damage. We’re experiencing this in our orchards here in Northeastern Missouri. The trees survived, but they didn’t bloom and therefore didn’t set a fruit crop. Our neighbors’ peach trees to the south seem to have been spared, as they bloomed and are now in the early stages of fruitset.

      In your case, your peach trees may take this growing season to store energy and nutrients, rather than bear a fruit crop, in preparation for next year — and hopefully the weather is in favor of that! :)

      • Gary Dreher permalink

        Yes, I forgot to say that I’m in Champaign, IL, a little north of your nursery and further east. So I expect no peaches this year, but it looks like we’ll enjoy pears from our five-year-old tree this year for the first time.

  7. Emily permalink

    I have a question about a 3 year old methley plum. I scratch tested it and it’s alive, but it doesn’t have one leaf bud or leaf yet and I’m in the Mid-Atlantic. It’s branches are all red, but no growth. All of our other same year trees are doing great with lots of leaves. We’re not sure if we should throw in the towel and get another tree (supreme size to play catch up quicker) or give it more time. Your help is appreciated.

    • I’ll always recommend giving a tree more time, especially after an unusually harsh season (like this past winter). Since you’ve already tried the scratch test, you could try pruning some of the limb tips back. This will be to see what’s going on with the tree now that you know it is still living, because it may be suffering from unseen winter injury.

      When you prune a limb back, look at the center of the limb that remains attached to the tree — the “heartwood” as seen in the illustration in the article. If this wood is dark at the center, you’ll know it has been damaged, most likely by cold temperatures. In this case, prune the damaged limbs back to healthier wood (it will be a lighter brown) and stop pruning as soon as the damaged wood is no longer visible. This should also encourage your tree to force growth from the buds below your pruning cut.

      If you find no damage in the limbs, then it should be a good sign. It may just need more time (and maybe a little fertilizer?) :)

  8. Lynn permalink

    So my North Star Cherry died.
    Or did it? Or what happened?
    Something ruined the bark on the trunk. It did not grow or flower last year. It looked dead.
    The bark is split open showing the “core” inside. There is another long split on the opposite side. The little tree is only a few feet high and about 2″ diameter. (Maybe it was the sun, or the freeze or what?)

    I bought a different variety little tree to take its place and planned to cut it down this spring.

    The poor thing grew, flowered and is full of cherries this year! Now it has grown more than 5″ of new growth. What has happened? How can it be alive? I guess no one can predict its future.

    • Wow! I’m not sure what happened, but it sounds like your cherry tree likes to keep you on your toes. :) Let us know how the fruit turns out.

  9. Gail permalink

    Hello-
    Planted 10 bare root raspberry canes the first week of March. All but two have shown some sort of growth; most from the roots, and a couple have foliage from the canes. The two that have not shown any growth are definitely still green inside when I cut the cane down a bit, indicating to me that they are still alive. The canes are about 8″ high. I would appreciate your take on why no growth. Anything I can do to encourage growth like cutting the canes lower? Thanks!

    • Good instincts, Gail! Pruning will certainly help stimulate growth (especially from the roots) in your raspberry plants. This is why we recommend pruning the canes back to two inches above the soil at planting time.

      You can read more about planting bare-root raspberry plants here.

  10. roland mcginnes permalink

    really like your help tips. I have a santa rosa plum about 15 yrs. old and 15′h x 12’round, beautiful tree but just puts on a dozen fruit or less every year. every thing else in our small orchard does great. the gratitude grape i ordered from you this year is growing like crazy with nothing but watering so far….

    • I’m glad you find the information useful, Roland! Keep us posted on how your new grape and everything else grows for you. It sounds like you have a green thumb :)

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