Roots, Shoots, Fruits & Flowers: More Potassium Deficiency, Dark Honeybees & Soil Moisture


A tomato leaf with suspected potassium deficiency.
Photo: Melissa Harris.

Potassium deficiency in tomato plants

In recent weeks, several gardeners have shared pictures of tomatoes with symptoms on the leaves and wanted to learn of a possible cause.

AHA suspected the early stages of a potassium deficiency in these tomato plants because the leaf margins will become brown with dead leaf cells. Potassium is important to plants for disease resistance, drought resistance and better nitrogen efficiency.

Dr. Kiki Fontenot, a vegetable specialist with the AgCenter, shared some comments about applying potassium fertilizer, “I think your suspicions are probably correct. I like alternating potassium nitrate (greenhouse grade) with calcium nitrate (also greenhouse grade) on vegetable crops. This gardener could probably find potassium nitrate at a hardware store or plant nursery – lots of times they will break down larger bags into 5 lb. portions if you ask. KNO3 is about 13% N so, I would use roughly a tablespoon per gallon of water and water each tomato plant weekly with the solution (maybe a ¼ gallon per plant). Potassium nitrate is water dissolvable, but it usually takes hot water for it to really dissolve. Ask this gardener to try using this and calcium nitrate for 4 weeks in a row, alternating them and see what happens.”


A closeup picture of very dark honeybees.
Photo: Justin Landrum.

Dark honeybees

Justin, a beekeeper in Anacoco, sent a picture of some unusual honeybees, and shared some of the story about these bees, “I caught a swarm last year that was mostly black bees. I did not pay much attention to them [and] just placed them in the apiary next to the other hives. This spring they are doing very well. They are strong and occupying 4 deep [hive boxes]. Like I said before, the bees are black with a little bit of a white stripe.

The reason I am contacting you is to find out if this is a different species than the Italian bee? They are very aggressive and [half the hive] the hive [seems to] come out after you when inspecting. I have always heard the locals saying watch out for the little black honeybees, they are mean. I heard that they are a German bee but don’t know what fact is and [what is] legend.”

The first honeybees in America were the German black bees. However, the Italian honeybee breed with the classic black and yellow coloring is very popular among beekeepers for their honey production and gentle behavior. If you have observed these dark honeybees, feel free to share your experience with RSFF.


A tomato plant suffering from drought stress.
Photo: Cornell University.

Soil moisture

Denise asked via email, “What should my moisture meter read for my young tomato plants? They are about 4-5 inches high.”

Again, AHA consulted with Dr. Kiki Fontenot, and she share her thoughts about this question, “I have seen several moisture meters with varying number ranges, like 1-10 or 1-100 and even 1-8. The most important thing with tomatoes is a little moisture each day which sounds crazy because we often promote deep infrequent irrigation to promote roots to grow deep. But that is really for perennial plants. Tomatoes need calcium even early in growth, not just during the bloom and fruiting period. Calcium primarily enters a plant through the roots. Then when the plants have fruit, they can easily crack if overwatered… so a little water each day - not allowing the plants to wilt is the best advice I can give. How long? Depends on if you are in clay or sandy soils and how big the plants are. I am on drip irrigation and clay soils. I start with 20 minutes per day and increase to 60 when at full harvest and the plants are 4 ft tall. If I were on sandy soil, I would reduce that time by half or more, and may consider twice a day irrigation if we are getting absolutely no rain… but only on sandy soils.”

If you want to contact Roots, Shoots, Fruits and Flowers, please send your questions and pictures to Keith Hawkins, Area Horticulture Agent (AHA), 337-463-7006 or Also, you can be on the “green thumbs” email list by emailing your request to the address above.

“This work has been supported, in part, by the USDA National Institute of Food and Agriculture, Renewable Resources Extension Act Award, Accession Number 1011417.”

4/29/2020 9:02:29 PM
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