Iron Chlorosis in Raspberry plants
I think that my raspberries planted in clay soil have iron chlorosis, eg yellowing of leaves, spindly growth. What can I do to change the ph of the soil and get more iron available for the plants to become greener and healthier?
Multnomah County Oregon
Thank you for choosing Ask an Expert for help with your raspberries. Iron chlorosis occurs when there is too little iron in the soil (unusual in natural soil in the Willamette Valley) or when a high pH makes iron unavailable (also unusual in the acid soils of our area). In a raised bed, with a high organic matter blended soil, this condition is more possible.
Iron chlorosis generally affects the leaves at the top of the plant first, leaving the lower leaves green. The affected leaves will begin to yellow between the veins, leaving the veins green. If it is iron chlorosis, finding out the cause is the first step. Inexpensive pH kits from a garden center can help determine whether pH level is the problem. Raspberries prefer a soil pH between 5.5 and 6.5.
For a full soil test, choose a laboratory to assist you. There are a number of alternatives in this Extension Service publication. See here: https://catalog.extension.oregonstate.edu/em8677
The website of the laboratory you choose usually provides information on taking a sample and shipping it. Or give them a call. One to two cups of soil should be enough for the standard garden nutrient tests. Be sure to provide the requested information on your garden site to the laboratory, and request fertilizer recommendations for your particular situation and what you plan to grow.
There are several disease and insect problems that lead to yellowing canes in raspberry. If adjusting the soil does not resolve the problem, please contact Ask an Expert again, for additional assistance.
Have a good gardening year,