Hi----

I've recently noticed that the leaves on trailing verbena in 12" pulp baskets are drying up until they crumble. It is happening slowly, but working it's way through the whole plant. They are combined with lobelia, petunia, nemesia and those plants aren't dry, but do show a little purlpling like a phosphorus deficiency. As far as I know they haven't been allowed to dry out and crash.

The pansies are a different story. They older leaves are completely drying from the tip back or the sides inward. What's left is papery, pliable, brown tissue. I've tested their pH and it was high (7.2). I've added more sulfuric acid to our water to lower the hose end pH. They have been kept at the appropriate temperature and moisture. The problem is sporatic, but prevelent in the older pansies (planted from 288's about 3-4 weeks ago).

Both crops are getting fed 20-10-20/14-0-14 @ 250ppm alternating with epsom salts and calcium nitrate.

Any insight?

Hi Lacey -

The high pH could be resulting in some nutrient issues and phosphorus is less soluble to the plant when the pH is high. Also the two crops you specifically mention, verbena and pansy, are considered iron-inefficient species. This means when the pH is high these species are inefficient at taking up micronutrients.

You can see some purpling of the older foliage on a number of species if phosphorus is deficient. Other causes for the purpling can be cold temperatures, nitrogen or zinc deficiency, root rotting, and excessively wet media. Some other things to check would be temperatures, especially your nights and make sure they are in the optimal range for all your crops. Check the root health and make sure there are no signs of disease. Most things in the greenhouse now should be allowed to go through good wet/dry cycles between irrigations, make sure you aren't overwatering.

To make sure your nutrients are in check and before you change your fertility program you may consider sending in some tissue samples for analysis. You are on the right track by taking steps to lower the pH but you will also want to investigate reasons why the pH is high to begin with. The pH on a pansy crop will increase throughout the course of the crop and it is important to continue with your weekly testing and always make the necessary adjustments to your fertility program and water source to keep the pH lower.

Hi,
I had the same problem on my Verbena. The source of my problem was Thrips. After a good spraying and I cleaned them up they now look beautiful. I had no idea we were infested till
we did the white paper test and found 1000's
of little worm like larve. I did not notice that many adults. Yellow cards were not showing anything that I thought was a problem. Boy,was I wrong. The white paper test is simple. Hold a piece of 8x10 copy paper under a branch and vigerously tap it. Then examine what you find on the paper. I hope this helps.