Cole Crop Pointers

September 11, 2023

Cole crop production (broccoli, brussel sprouts, cabbage, cauliflower, kale etc.) has been a challenge on many farms, particularly fall plantings, with black rot and Alternaria creating the biggest difficulties, although there are certainly other challenges as well.

Flea Beetles love cole crops that are low in energy, or high in nitrates or free amino acids. For energy, use the basic application of drip-applied calcium, Epsom salt, and plant derived 7-7-7. For high nitrates or free amino acids, we look at 2 qt. Rebound Molybdenum, 2-3 pounds Potassium sulfate, along with SeaShield. This has been foliar fed with decent success. Epsom salt may also improve resistance.

It is critical to maintain adequate levels of boron. Cole crops utilize lots of boron. Boron deficiency, when severe enough, will cause hollow stems. Once you have hollow stems, nutrient and water uptake is greatly reduced and it is nearly impossible to produce healthy plants.

It might also be worthwhile to point out the head of whatever cole crop you are growing is NOT a fruit. Instead, it is the result of vegetative growth, which means that you can increase the speed, size, and quality of production by pushing the major growth minerals, which are calcium, potassium, nitrogen. SeaCrop and boron also help. When this is implemented properly, growers have been able to get larger heads quicker, and without any signs of bolting.

When the plant is starting to bolt and push a seed head, it is a sign that the plant has too much reproductive/fruiting energy, or is reaching its maturity date.

Finally, we discuss nutritional options for disease control. I would be remiss to not note the qualities of calcium, boron, silica, and potassium in general disease control. Calcium, boron, and silica all help to build the pectin levels and cell wall strength in plants. When these pectin levels are build up to adequate levels in plant cell walls, the water in the interstitial spaces is dried up, effectively removing the breeding ground for plant infection. Potassium, on the other hand, improves resistance to disease by providing energy, reducing levels of free amino acids, improving nutrient uptake, increasing the efficiency of water and photosynthesis, and activating about 60 different enzymes related to plant growth processes. We have seen many instances where potassium has improved disease resistance, and certainly it is important for resistance to black rot.

Conventionally, these diseases are also being battled with copper. Copper certainly improves disease resistance for many crops; however, I would offer that it may be an incomplete perspective. Should we also be looking at zinc? I think it is especially important for black rot, being a bacterial disease. As Don Huber points out in his book, Mineral Nutrition and Plant Disease, zinc is the most effective trace mineral for managing bacterial diseases.

In light of this information, you may want to consider applications of 2 qt. Zinc and Copper as a foliar, and combined with SeaShield for immunity. We could also consider potassium with this. Next, I would consider drip-irrigating silica, with a 5-10 pound rate of 20% calcium, 3-5 lb. rate of Boric acid, and 1-2 qt. Molybdenum.

In summary, fall cole crops are a challenge. But with proper nutrition, starting from the ground up, it is certainly not impossible to grow a healthy crop. Experiment. Ask your consultant for additional ideas. Take some sap tests to help you figure it out on your farm. And let us know what is working for you!