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Growing Points: Avoiding crop losses

March 27, 2012  By Dr. Mohyuddin Mirza

This is April and calls and e-mails are coming in with various problems.

This is April and calls and e-mails are coming in with various problems. Since problems are recurrent every year, I want to share this particular one. This is a real story and all of us can learn from this and avoid economic losses by proper diagnosis of the problem.

Photos sent in by the grower, showing good plants at left, and affected plants at right.  

”Hi Dr. Mirza: I have attached two tomato pictures, one bad and one good. Patio variety. The curling showed up slowly about two weeks ago. We have been feeding 20-9-20 and 13-2-13 at 225 ppm. I have sprayed these tomatoes with B-Nine four times at 3,750 ppm or .375 per cent, which is our normal rate for all our tomatoes whether in 4”, 10” or 12” (containers). We have grown the same variety in the same cold frame on the floor for years. No pesticides have been used at all. Fuchsia baskets were grown overhead and received the same fertilizer, no problems. Our water comes from a dugout on the property and we are not aware of any spraying close to it. We spray Roundup in the summer but are careful to avoid the dugout. No herbicide spraying of any kind has happened this spring. Our pH is 6.6 and the EC is 2.88 while feeding 13-2-13. The roots on both tomato plants are white and healthy.” 


Although I have labelled these plants as “good plants,” you can see strong vegetative growth and that they are very compact, which likely was due to applications of B-Nine. The affected plants are showing a strong curling of the leaves inward and are a light purple colour. When I enlarged the pictures, I was able to see cell juices oozing out and forming a corky deposit, typical of what is called “edema.” Growers are familiar with this on ivy geraniums.

This New Guinea impatiens had top leaves that were not expanding and also had bud abortion, which according to my experience was a deficiency of calcium. Many bedding plant growers don’t realize there is no calcium in most of the fertilizers they are using and that calcium from water is not enough to support the growth of the plant. 

The e-mail continued: “Phoned another grower a week ago and shared the above (information) with him. We talked about environmental problems he had read about. Too much sun all of a sudden. The shaded half of the cold frame was not showing as much curling as the other half. So we swapped some plants to the shaded side and they seemed to look better in the morning. We also gave them a really good watering in case it was a feed issue. They are all dark green. They have just gotten worse.

“The owner wants me to throw them all out, roughly 400 pots and now it is showing up in the 10” tomatoes in several other varieties, nothing yet in the 4” but they are shipped faster. A few 12” tomatoes were sold and the customer has told me that they are doing the same curling, and his water is from the town. I did EC and pH soil testing from both pots but forgot to bring the results home with me. I do not have computer access at work. If you need more information or pictures please let us know.”

It was signed: “one grower at wit’s end.”

I was impressed with the ability of grower to describe the symptoms and the summary that was supplied of what has been done up till now. After looking at the pictures, I called immediately because the affected plants may have been thrown out and an economic loss may have occurred. After talking to the owner, the following e-mail was sent:

  • 1: Tomatoes: They are showing symptoms of odema or edema. It is a physiological disorder in which the nights are cold and the days are hot. When night temperatures drop rapidly, cells in the leaves burst open. That is why you see a corky-like material (which is plant sap) on the curled leaves, veins and petioles.   I suggested increasing the night temperature to close to 16-18ºC and see if the day temperature can be controlled closer to 22-24ºC. Plants are very vegetative due to being grown in cold frames.
  • 2: New Guinea Impatiens are showing calcium deficiency. I suggested they use calcium nitrate 15.5-0-0 at one gram/litre, and also check to see if they are being grown at cooler temperatures, like the tomatoes. There is a possibility of some thrips damage in the top leaves.

“Let me know about the progress of the plants,” I wrote. “Thanks.”

A second e-mail came from the grower giving more information on plants in these cold frames.

”Dr. Mirza, I forgot to explain about the other pictures I included in the first e-mail. You mention that tomatoes were the first indicator plant and I am wondering about our New Guineas and fuchsias.

“Some 50 baskets of fuchsias have aborted their flower buds and some 4” New Guineas have started to curl with the new growth. I do not know if they are connected or unrelated. Neither has been sprayed with B-Nine. Same fertilizer applied. I have not done EC/pH on them.”  

After that, I did not hear what happened, but like any curious person I was wondering if things turned around or if my recommendations were followed. The grower got too busy and then an e-mail came at the end of the year.

“Happy New Year, Dr. Mirza: I am an assistant grower and I work directly under the head grower. We have been very busy up until now and it was discovered that we had not kept you informed of the tomatoes and New Guinea impatiens we had problems with in the spring 2011 growing season. Our apologies for how late it took to get back to you, many thanks, and an update.

“Because of the information you provided, we were able to save five cold frames of tomatoes. We threw out 400, 12” tomatoes, (or gave them to staff), that were too damaged to ship to consumers.

“I myself took home a number of the better looking ones to observe their progress. Some flowered a little, but did not begin producing any fruit until about September. By then frost was just around the corner and we harvested very little from them. The others just did not do much of anything.

“We adjusted the heat as recom-mended and we had no further problems. We will definitely be monitoring the temperatures carefully this 2012 spring season to avoid the same problem.

“In regards to the New Guinea impatiens, we only lost about 30 plants. We were unable to get sufficient calcium nitrate into the plants fast enough to deal with the situation. We had relied on our supply of 13-2-13 and it did not do the job we needed it to. In the future, we plan to maintain a supply of 15.0-0-0.

“That is all for now, but I’m sure we’ll be in contact again sometime this spring season, if only to let you know we had an excellent growing season! (I guess I’d better not count our chickens before they hatch.)”


  • Don’t be afraid to call or e-mail if there is a problem, but do it early enough when you suspect there is a problem.
  • Opinions of different people can vary, based on their experience and knowledge. Ask questions as to why they think that this is the problem. Filter out the information and then use it.
  • Communicate more effectively. In this case, I did not hear if the plants had responded to my recommendations.
  • Don’t be ready to throw out plants until you are sure what is going on. One can always isolate such plants in the beginning.
  • If owners are getting too busy, they should send their staff for training to conferences and workshops, and to visit other growers.
  • Understand the basics of fertilizers and plant nutrition. Calcium is not present in many formulations. It is only recently that we have begun seeing some fertilizers with calcium in them. For example 12-2-14 has six per cent calcium.

Remember, when you use ready-made fertilizers, the amount of calcium will depend on its ratio in relation to other elements. For example, if you use one gram of 12-2-14 in one litre of water, you will get 120 ppm of nitrogen, 20 ppm of phosphate, 140 ppm of potash, and 60 ppm of calcium.
Have a great growing season.

Dr. Mohyuddin Mirza is a greenhouse consultant. •

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