Have you found Black Walnut to hurt your tomatoes/fruit trees? In your personal observation?
I have grown tomatoes for over a dozen years on this property. I have several mature fruit trees (15 years old or more) Cherry, Plum, Apple, Fig, Persimmon as well as Mulberry, Blueberry. And many new ones (loquat, pears, quince etc.). They all do decently well.
Oh, I also have several Japanese Maples not far from the Black Walnut. They are also doing very well.
Inconsistent results have been the bane of juglone allelopathy research. For every report of toxicity in a tested species, another report will find no effect. Researchers have pointed out a number of problems with initial assumptions and laboratory trials, which are summarized below: • Juglone, a highly toxic chemical, is not found in intact tissues of black walnut trees (Strugstad and Despotovski 2013). Instead, living tissues contain a nontoxic precursor called hydrojuglone, which is transformed in the soil to make juglone (Achatz and Rillig 2014). • Most hydrojuglone is contained in the roots and shells of walnuts (Figure 2). There is little in the leaves and virtually none in the wood (Lee and Campbell 1969). • Many researchers use artificial experimental methods to test for allelopathy. For instance, soilless media and laboratory extractions of juglone from walnut tissues do not occur in nature (Inderjit and Foy 2001). • Allelopathic responses are enhanced when potting media are used instead of soil. This is attributed to the increased permeability of the media compared to soil (Parepa and Bossdorf 2016). The lack of field test evidence to support laboratory results has spurred critics to insist that experimental testing include a functional soil system to more closely mimic what happens in nature. They note several conditions and activities that may account for the lack of positive field test results: • Juglone undergoes chemical, physical, and biological degradation in the soil (Inderjit 2001). • Organic matter and clay particles in soils can bind juglone, reducing its movement within the soil (Inderjit 2001). Figure 2. Walnut surrounded by husk. Photo courtesy of Monika Pickles. • Juglone does not persist in soils with high microbial activity (Jilani et al. 2008; von Kiparski et al. 2007).
And the conclusions by the authors:
Mulch well with arborist wood chips to retain soil moisture and to nourish beneficial soil life including mycorrhizae. • Enjoy your walnut trees! Not only are they robust landscape plants they provide food and habitat for wildlife. In areas with thousand-cankers disease, however, they should not be planted. • Use walnut wood chips for mulch if you have them. They will not harm plants and work just as well as those from any other woody species.
Have you verified you actually have a black walnut.?
Pecans, white walnuts, hickory…all have some juglone…but not nearly the same quantity/dosage.
Besides raspberries, sweet potatoes, tulips, daylilies, daffodils, oriental lilies, Lenten rose (helleborus), catmint, wormwood, golden rain tree, juniperus virginiana…………are some trees and plants I know will grow under a black walnut. The jury’s out on mountain laurel and deciduous azaleas…in other words I’m trying it and they look a little sick.
K8t, I have muscadines growing in and all the way through the crown of black walnut trees with no issues. I would still avoid planting a muscadine in any area where a tree’s roots will be in competition because it will reduce production of fruit.
Ramv, do things your own way. I have no interest in disagreeing. What I do have is 50 acres of black walnut trees growing and producing walnuts. I also grow about 350 tomato plants each year. If you guess that I don’t plant tomatoes in the walnuts, you are correct.
Does anyone know of nut-free cultivars of eastern black walnut? If they existed they would be a quick-growing shade tree. They have some problems - their compound leaves have sort of messy stems and the alleopathy. But good God, the rain of Freeman maple samaras was like snow in our neighborhood this year. So even they have their problems (e.g. poor branching structure).
I also have a friend who has a small orchard in his spacious front yard. At the corner stands a large BW. Trees within 40 ft of it are stunted. He basically gets all his fruit from past the 45 ft line. he should trench at 30 ft.
Maple helicopters are the worst…especially if you have open gutters.
MY mil needs a new tree (west side of house). She had a maple but it had dual trunks and split right down the middle. Too bad because it provided a ton of shade. I think i’m going to plant a seedling oak in its place. Red oak. Don’t see a lot of them as yard trees around here.
Hmmmm… I think a park near here was hit bad with that a few years back. Pretty soon we won’t have any hardwoods left! With elms, ash all toast… I do have some burr oak seedlings…they just seem a little slower growing then the reds.
“Oak wilt is always fatal to trees in the red oak group, which includes northern red oak, northern pin oak, and black oak. Trees that were infected with the oak wilt fungus this spring will begin rapidly dropping their leaves in July and August.”
I didnt’ realize it was fatal to the tree. I’ll have to check mine over (i have many).
My brothers just had about that much land logged west of Black River Falls. I guess i never heard them mention oak wilt. I know the loggers were leaving a few trees to reseed the land but everything else was taken out (clear cut). I haven’t been up there in a few years.
You won’t have to check yours over very carefully to find it if you get it. The whole tree dies rather suddenly, beginning with the tiptop branches all suddenly wilting, then the whole tree dying in a few weeks. Plant your mil a white oak, as they don’t get wilt.
Over on the NNGA Facebook group someone suggested that Juglans regia x nigra are generally sterile. But if so, the darn trouble there is also finding a scion, and whether or not they’d be Z5 hardy.
Burr x swamp white oaks are fairly fast growing. Bebb’s oak I think is the name. Oikos sells them.
Lots of cities are planting more and more hackberry. Such a bummer of a tree. No flowers, no fall color, and doesn’t grow really big. The University of Iowa grounds folks are super fond of them, and have planted hackberry extensively.
Oh…40 feet plus…and big as a 55 gallon barrel isn’t big? That’s what hackberry can do.
The fruits are not good…birds eat them as a last resort. (After all the feeders are snowed over or the squirrels ate them dry.)
I have a Burr oak. Loaded with acorns again. Fast growing, but the thing loves to hold its leaves all winter. Finally late spring and it sheds them and leafs out. I guess you don’t have to rake in the fall.