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Ruth Gonzalez PhotoDear Ruth,

A question on my blueberry bushes.  I scratched in some Hollytone the other day as my bushes are forming tons of berries and then I watered well.  Now I have some dead branches and yellowed leaves and lots of leaves have fallen off?  I have completely bare branches with just berries on them.  What happened?

Mary B.

Dear Mary,

It is hard to say exactly why your blueberry plants are defoliating (losing their leaves). Here are a couple of possibilities:
Blueberries

    1. When you scratched in the fertilizer, you may have scratched too deeply and damaged the roots or burnt the roots with the fertilizer. Blueberries are shallow rooted, so be gentle when you scratch in fertilizer and be careful not to disturb the roots. Consider just watering in supplements.
    2. Did you apply the recommended amount of Holly-Tone? Always read the directions, and follow the recommended rate of the particular fertilizer you are using. You don’t want to over-fertilize by accident and chance “burning” the plant. Acid-based fertilizers like Espoma Holly-Tone, Happy Frog Acid-Loving, Fertrell Holly Care, and Fertrell Berry Mix are good choices for blueberries whose ideal pH is a low 4.5. Before fertilizer application, certified growers should check with their certifying agency to be sure these fertilizers are approved. Timing? I don’t think timing would affect your leaves, but fertilize blueberries when the flowers are opening and again about one month later.
    3. My gut says the problem was lack of water. I think your plants are thirsty. We have had a very dry summer. Although blueberries don’t like wet feet and they demand good drainage in their root zone, they DO enjoy consistent moisture and they can revolt (and even die) if allowed to go bone dry. A newly planted blueberry should be watered twice a week DEEP (to the bottom of the root ball) for the entire first year (12 months) with a mini-holiday during winter. Even well-established blueberries can die if allowed to go bone dry. For your already established blueberries, it is a good policy to give them a nice deep drink when you are watering other plants in their vicinity, or make an effort to give them some water every two weeks or so during dry years. Mulch is a good way to help your plant make better use of rainfall plus protect the roots from winter damage. Consider mulching with 2 inches of wood chips each year (always water deeply before mulching as the mulch helps retain moisture in the ground). I almost killed one of my blueberries from lack of water. It took me a while to notice that the branch tips were dropping leaves and dying back. Once I started watering consistently and deeply, the plant revived (thank goodness!) – but I had to baby that blueberry for a year or so, and I continue to water it during dry spells.
    4. There is a fungal disease called Twig Blight of Blueberry. This disease overwinters and shows up relatively early in the growing season. I don’t think this is your problem because you had lots of fruit on your bushes, but check out this article from NC State Cooperative Extension to learn more.
    5. Your problem could have been a mixture of issues – like root damage and lack of water or some other combination of possibilities. As with all plants, the blueberries immune system will remain stronger when we are able to adequately care for and anticipate their needs throughout the season. Unstressed plants will be in a better position to stave off challenges if they arise. Most woody plants can tolerate defoliation once or twice, but they will be more productive if we are able to keep the foliage happy and on the plant through the growing season.

blueberries copyLooking for more info on blueberries? Check out this Ask Ruth article on Blueberries and this Ask Tom article on a new pest of blueberries.

Thanks for writing Mary, and I hope this answer reached you in time to be helpful.

Best wishes,
Ruth

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Ruth Gonzalez

Ruth Gonzalez

Ruth Gonzalez is a former market farmer, current gardener, and local food advocate. She has written numerous local food and gardening articles, blogs about local food, and writes the “Ask Ruth” Gardening Column for Organic Growers School. In her job at Reems Creek Nursery, Ruth offers advice on all sorts of gardening questions, and benefits daily from the shared wisdom of local gardeners. She has a special affection for clouds and finds delight in the natural world at every turn. Read more from Ruth at her blog: http://tailgatemarketfanclub.wordpress.com/