Root Rot and Wisterias
Question from Judy:
My Wisteria – 9.5 years old — just stopped growing and leaves began yellowing and drying. I cut back some wood that had not leafed out and it was dead. When I looked up these conditions, it said it could be Cotton Root Rot. Have you ever seen or experienced this? The article also stated that it was usually fatal. Yikes! Am I going to lose my beautiful Wisteria? Is there anything I can do? It’s actually happening on both front yard and backyard Wisterias.
Answer from Pat:
I’m sorry your wisterias are dying from root rot. They are perhaps already dead. There may be nothing you can do to save them, but don’t become discouraged! You will just have to find a spot with better drainage and replant. That’s what I did at my house. See the story Chapter 7, “The Wisteria That Would Not Give Up,” in my first memoir: “All My Edens: A Gardeners Memoir,” published by Chronicle Books in 1996. (Long out of print but you can find used copies on the Internet.)
Not sure where you live but in Southern California where I live rains were heavy this winter. Yes, a wisteria could certainly die from root rot. This does not need to be Cotton Root Rot, but any root rot. Wisterias need good drainage. When I planted my first wisteria 50 years ago I knew that, but I didn’t know the correct way to provide it. I built a sump instead of a drain. A sump consists of a narrower hole dug on the bottom of a planting hole and filled with rocks. Years ago it was mistakenly thought to help drainage but of course it did not. Instead, it simply filled up with water thus provlding an underground swimming pool for roots. Roots went in there and soon rotted. This killed my first wisteria. (The full story is told in the chapter mentioned above and I don’t want to spoil it by telling you the ending.)
But I can tell you this: A better way to improve drainage in poorly drained soil is to build a raised bed. The raised bed doesn’t need to be very high. Just 4 inches will suffice. Fill the raised bed with top soil mixed with the native soil and then dig your hole through the raised bed and into the soil below and plant into the ground that way. Also if drainage is poor due to the alkalinity of clay soil, then dig as much as half a coffee can of gypsum into the bottom of the hole before planting.
Thank you so much for the advice. I’m really sick about losing my beautiful Wisterias, but onward and upward, I guess. I’ve ready that we should not plant another Wisteria in the same spot. Is that true?
I look forward to seeing you at the Orange County Master Gardener’s event in September.
Hi, Judy:
It would be better not to plant another wisteria in exactly the same spot. However, if you have read the story I referred to before in “All My Edens”, you will learn that the wisteria I had that died of root rot came back to life again and is still alive today. (I won’t tell you the rest of it since I don’t want to spoil the story.)
The main thing to do is to provide good drainage. Wisterias, except for silky wisteria (Wisteria brachybotryis, W. venusta), are not adapted to growing in lawns. Don’t plant wisteria next to a lawn. If that’s where it is, choose another climber for that spot such as lavender trumpet vine (Clytostoma callistegiodes) that is not particularly fussy about soil, or plant W. brachybotrys there. (It’s highly fragrant and needs more water than Japanese or Chinese wisterias. I have seen it survive on the edge of a lawn.)
To plant Japanese or Chinese wisteria, begin with a good grafted variety. That way it will bloom the very first year after planting. Check the drainage as described on page 40 of my month by month organic gardening book and move the planting spot over and you should be able to grow another plant on the same structure you used before. Additionally, don’t give up hope. I planted 6 bareroot Chinese Wisteria (W. sinensis ‘Cookes Special’) on a long pergola in 1986. Two died of root rot. I still have a beautiful display of wisteria on that pergola. I cut it back massively (3 or 4 feet lower) but by stages last summer since the wood had gotten too heavy on top. Since we cut it back correctly (always just above green growth so we could cut again after it sprouted lower) it still bloomed spectacularly in spring.
Thank you AGAIN!
I have had great success combating root with with a product called “Aquashield” by Botanicare. It’s made of some sort of compost solution and has good bacteria to fight the bad bacteria with root rot. After making sure that you’re not overwatering your plants and checking that they have good drainage, then you can help the plant recover by feeding it some Aquashield every few waterings.
Thank you for informing me of the product “Aquashield” by Botanicare. It is a liquid fertilizer useful in aquaculture and hydroponics. It is
made from composted chicken manure and helps emphasize to all of us the health-giving properties of manures. I lived on an organic chicken farm during the
Second World War and found out the many benefits of chicken manure in the garden.
Regarding battling root rot, there is also a patented product that was originally developed as an African violet fertilizer
that is called Oxygen Plus. It is useful for feeding houseplants since it keeps plants alive even for people who tend to overwater them.
Oxygen Plus actually puts bubbles of air next to the roots of plants, but it is not an organic fertilizer. The product
you mention, “Aquashield” is evidentally an organic product, though a highly refined one.