Lack of green on some marionberry leaves.
Some of my marionberry new grow does not have fully green leaves. Veins are green but rest of leaves are pale whiteish. Most plants nearby are fine. Have fertilized. Will adding Epson salts help? This is a home garden with six plants in a 20 foot row.
Multnomah County Oregon
There are several possible causes for the lack of green on some of your marionberry leaves from viruses to winter damage to herbicide drift. However, the most common cause for the color change, called chlorosis, is iron deficiency, usually from a soil pH that is too high (too alkaline). Berries prefer a soil pH of 5.6-6.5. Our native soil is slightly acidic with a ph between 4.8-6.2, but lime applications raise the pH and make it more alkaline. A pH test on your garden soil around your marionberry would be important to rule this cause in - or out. You can get pH test kits from your local garden soil, or have a soil test performed. The soil test will cost less than a pH kit and be more reliable. This lab, A&L Laboratories http://www.al-labs-west.com/services.php?section=Soil%20Analysis, has offices in the Portland area. Add a couple dollars for professional advice on how to change any deficiencies or excesses. This article has additional information on Iron Chlorosis in Berries https://digitalcommons.usu.edu/cgi/viewcontent.cgi?article=1710&context=extension_curall.
If the cause is a virus, more leaves will turn yellow, and you may need to replace your plants with disease-certified planting stock in a new area of your garden. If the cause if herbicide damage, it would be a good idea to determine the source. Your marionberry plant may outgrow it. If the cause is winter damage your plant will probably outgrow it.
This article from OSU has good information on growing blackberries, Growing Blackberries in Your Home Garden https://catalog.extension.oregonstate.edu/ec1303/html.
Thanks for your response. Can you suggest a product for a residential garden that will lower ph or provide available iron quickly?
thank you. Paul
It's very difficult and takes time to change the pH of garden soil. This article gives advice on how to do this, Acidifying Soil for Blueberries and Ornamentals West of the Cascades https://catalog.extension.oregonstate.edu/sites/catalog/files/project/pdf/ec1560.pdf. You really need to measure pH before trying to change it so that: 1. you know that pH is what is causing the yellow leaves on your marionberry. As we discussed, there are several causes of yellow leaves with green veins, and 2. you can do a 2nd pH to see if you achieved your goal to a pH better suited to your marionberry. Higher pH changes the soil so plants take up calcium instead of iron. Your soil can have plenty of iron, but your marionberry can't use it if the soil pH is too high.
The only way to get a quick fix for soil pH is to replant your marionberry in a raised bed with acid-loving potting soil available from nurseries and garden centers. You could try using acid-loving potting soil as a mulch, but I'm not sure that would work.Epsom salts is a good source of magnesium, and for soils with magnesium deficiencies can really help. Our soils have plenty of magnesium, however, so it won't help