Chlorosis - abnormal reduction or loss of the normal green coloration of leaves of plants, typically caused by iron deficiency in lime-rich soils, or by disease or lack of light
I love black eyed peas. Each year I dedicate more space in my garden to black eyed peas than any other vegetable. This year is no exception. I currently have two 33 foot long rows of pink eyed purple hulls growing. Of those 66 feet of peas about 55 feet of them are doing fine. The vines are big, dark green and producing lots of purple hulled peas. However, a group of plants right in the middle of one of the rows is not doing very well. They are bright chartreuse in color and they are not producing peas.
My chartreuse peas are suffering from a condition called chlorosis. Chlorosis is a condition where plants do not produce enough chlorophyll to properly support their growth. Because of this lack of chlorophyll, chloratic plants produce foliage that is yellow to yellow green (or even white in extreme cases). Chlorosis happens when something in the soil prevents the plant from taking up enough iron (or magnesium). Both iron and magnesium are necessary for proper chlorophyll production
I have grown peas for years and I have had absolutely no problems. However, I grew them in raised beds that I had amended with lots of river sand and compost. These peas are growing in ground in a “new” garden that I started last fall. The fall garden did fine– no problems with chlorosis. Because of the early success in the new garden, the unmistakable signs of chlorosis on my peas really surprised me.
Cause – Even though I knew what was wrong with my peas, I did not know what to do for them. So, I did the only thing I knew to do; I contacted my friends in extension horticulture. I am very lucky to be friends with some truly talented horticulturists. Whenever I have a problem I send them pictures and a description of the problem. You can do the same thing. Most extension offices have people that can answer your plant questions. Do not be afraid to contact them. It is their job to answer your questions and they love to hear from.
My first response came from Cynthia Mueller. Cynthia is a volunteer with extension and one of the most knowledgeable plant people I have ever known. Like me, she was interested in the fact that the problem was isolated to a certain part of the garden. Our discussion reminded me that I once had a burn pile in the exact same place that was now experiencing the problem. Next, I heard from Greg Grant. Greg is definitely one of the top horticulturists in Texas and also the most successful plant breeder around. When I told him what Cynthia and I were discussing he became convinced the burn pile was exactly what had caused the problem. I grow in the alkaline black clay that is common in the central part of Texas. Greg reminded me that since black eyed peas prefer a soil pH of 6.0 to 6.5 my alkaline black clay (high pH binds up iron) was not the best environment for this variety. In addition, the burn pile added a lot of phosphorous and lime (both of these also bind up iron) to a soil that type that is already known to tie up iron. So, I am trying to grow these acid loving peas in an environment that is just not suited to them.
Treatment – There are two ways for me to correct the chlorosis in my peas. One is a quick fix and the other involves making changes to the soil. My buddy Tim Hartman (who is an extension agent) sent me some very detailed instruction on how to do both. Here is Tim’s response:
“Different cultivars can vary some in their efficiency at extracting iron from the soil. Iron availability can also vary a lot from one part of the row to the other depending on factors like watering (water with high calcium would raise the pH) or whether you’ve applied a lot of phosphorous fertilizer (organic or inorganic) to that soil (ties up the iron). You could apply chelated iron as a foliar or drench if you have some, or try to lower the pH with some sulfur. Of these, the foliar iron chelate would give you the quickest response and the sulfur the slowest. “
So there you have it. I have chloratic peas because I am attempting to grow them in an area that is just not suited for them. I will be taking advantage of both of Tim’s suggestions. I am going to use a watering can to do an iron chelate drench. This should get the chloratic plants producing. However, that will not solve my problem long term. When I re-till for the fall garden, I will begin to add sulphur. I realize this is critical. Since most vegetables prefer a pH that is in the range of 6.0 to 7.0, I will always have problems with chlorosis if I don’t fix my alkaline, lime enriched soil.