My tomatoes were looking great last week. They were at the 6-7 leaf stage about 25 cm tall, and a perfect dark green throughout the plant.
Notice that the area outlined here is the same colour as the area outside the circle. It’s common, in my experience, that you will see symptoms of underfeeding here quickly. This plant looks very good, though.
I took this picture to show the height of the plants, thinking that I could check each week to get a better idea of how fast they are growing. This plant is at the 7 leaf stage and is looking very good to me.
This is the same plant at the 9 leaf stage.
We noticed this damage beginning on Tuesday. I measured the EC on that day and it was 3.74 mS/cm which is way too high–especially for young plants. We immediately leached the coir media that we grow in with water and seemed to have stopped the damage somewhat. I measured it at 3.42 mS/cm today, which is still very high. I expect that there is also root damage and that this crop is set back somewhat. (Note that the pH measured a perfect 5.8 both days.
We have been having some problems with our injectors and we are waiting for parts. One of the problems with growing outside of a major greenhouse-growing area is that it is difficult to get parts quickly out here. I hope that they come tomorrow and that we can start to fix the injectors. I keep calibrating the injectors each day, but it appears that the damage is on the diaphragms which push material into the irrigation water. They are misshapen and so they act irregularly. Normally I would make very minor adjustments to calibrate them about once every month or two. Now I’ve been doing it at least once a week and often have to make big swings, and so it is difficult to predict what is happening. We might also have a compounding factor of coir that has too much salt.
For the time being, I calibrated the injectors again, added extra leach programs (water and acid only) and set back the fertilizer injections to 1/4 strength which I will keep them at until I get EC readings down in the 2.5ish region and the injectors more consistent. I am also setting up manual measuring stations for a number of crops so I can start to measure manually what is going on and give greater over-site/control. The injectors I have are so nice and have worked so well for the last 4 years, but when they go it’s a huge problem. Hopefully we have figured out the problem and can fix it.
EC damage on tomatoes starts on the older leaves from the outside tips and leaf margins, spreading inward. The damage is lighter-coloured, paper-like necrotic (dead) tissue. On the picture above you can see the tip of the upper leaf on the picture’s far left just starting to show damage, while the middle and right have more advanced damage. The lower leaf is completely killed.
Its a stressful time for me.