Monitoring Vegetables during Fruit Fill

June 26, 2023

Successful farmers usually achieve their success by managing detail. While this is certainly important for all crops, it may be just a little bit more important for vegetable production, and especially so if done chemical free.

Today, we’ll share a few tips, mostly regarding nitrogen and potassium balance, but also a few other notes.

Onions bulbs should be monitored every day or at least several times per week. If you have a large field, you check a high spot and a low spot, pulling at least a five foot row of onions to monitor for disease pressure such as center rot, slippery skin, blue mold, and also for size. Most consumers are looking for a nice onion that has some depth to it but is also rounded out well. Nitrogen gives depth, while potassium and water fills them out nice and round. Potassium is often deficient in later stages. As for yield, the longer you can keep the onions out in the field, the more yield you get, as much as 5-6 extra bins per acre per week of delayed harvest. However, we also need quality so they store, so look for a balance between yield and quality. Cobalt helps delay senescence which also gives a better yield.

Tomatoes, just like all other crops, need energy to fill out fruit. An easy way to monitor energy is to watch the clusters. Are the fruit on each cluster setting at the same time, or are the king blossoms setting a week or two ahead of the rest? When energy is adequate, the plants will set all the fruit on one cluster at approximately the same time. As for nitrogen and potassium balance, what we talked about in onions also holds true for tomatoes. Tomato depth is achieved with nitrogen, while width and filling out is achieved with phosphorus and potassium.  When tomatoes are not filling out right, or have pointed tips on the bottom, it is usually potassium deficiency. Also monitor for insects and disease.

Zucchini should also be in full swing soon. Zucchini plants perform best with lots of heat and water. They need to be picked daily. Here again, I like to watch size. If the zucchini fruit is proportionally too short and fat, it needs more nitrogen. If it’s proportionally too long compared to thick, it probably has too much nitrogen. If the zucchini is pointed, it probably needs potassium. Potassium is almost always deficient when fruit is unusually pointed or not filled out. Also watch for powdery mildew.

Other basic points:

• Watering is another critical factor. Know your crops; do they like wet or dry, or in-between?
• Insect pressure is also important to monitor, as some of them can devastate a crop fairly quickly.
• Leaf expression – are the leaves nice and flat, or are cupped, twisted, curled?
• Brix content. The healthier the plant is, the higher the brix content, in general.

These are a few examples of what we look at when we go out in the field. All good points, but what I wanted most to bring out today is that you can monitor nitrogen and potassium balance somewhat just by monitoring the fruit. This is important for onions and tomatoes, but also for many other crops and should improve the quality and appearance of your fruit.