Seven Defoliation Strategies for Harvest Preparation
August 28, 2023 There are distinct smells those familiar with cotton production recognize. The smell after the first frost on cotton. The smell of freshly harvested cotton. And the smell of cotton harvest aids — the signal that the end of the season is near.
Leaf drop and boll opening in cotton is a natural process. Harvest aids help synchronize this process to facilitate a once-over harvest while preserving lint quality. Leaf defoliation and boll opening is an active process requiring the plant to do its part to ensure desired results.
Gauging current and future plant activity and its relationship with the upcoming weather is part of the complicated factors of planning a harvest aid program that is often referred to as much of an art as it is a science.
An effective harvest aid program for picker harvested cotton will result in essentially total leaf defoliation with little to no desiccated leaves, harvest ready open bolls in a timely manner, and little if any regrowth to ensure a timely and efficient once over harvest while maintaining yield and quality potential of the lint. (Photo: Bill Robertson)
Ideally, we want to approach the end of the season where available soil moisture and fertility are low, to the point that we have just enough left to get us to the finish line. Excess soil moisture and fertility can keep the plant in a vegetative state, making it easier to stick leaves as opposed to defoliating. A vegetative plant’s hormone balance has the potential to delay the boll opening process, resulting in a plant that is more mature than it appears.
The plant sets the stage for harvest aid strategies that will need adjustment with the passing of every weather change.
Seven Strategies to Preserve Yield and Quality
- Evaluate Maturity — Monitor and rank cutout dates to assess maturity of fields across the farm for initial planning. Boll slicing is the best gauge to determine maturity and often lines up very well with heat units beyond cutout guidelines for harvest aid applications.
- Evaluate Plant Activity — There is sometimes a fine line in the product rate in a very active plant between sticking leaves and having them fall. It is much easier to address green leaves left on the plant than to deal with desiccated leaves. Plant activity drops with the passing of each cold front and will require rate changes and more time to be harvest ready. Once temperatures drop to the low 50s and upper 40s, plant activity is reduced to the point that further maturity of fiber is complete, and little activity can be expected from hormone-based products.
- Know your Varieties’ Issues — Discounts for high micronaire can be avoided with an earlier timing of a harvest aid. Move these varieties up on your list when scheduling applications. Varieties that are less stormproof than others should be given special consideration to ensure they don’t have to wait in the field.
- Start Early — Often the greatest impact we can make on harvest aid timing is the initial application. Once we start our harvest aid program, applications are timed to keep the harvester rolling. The hours a harvester can run on the front end of harvest is much greater than at the end of the harvest season. Starting days earlier can cut weeks off the end.
- Optimize Application Techniques — Oftentimes we focus on just carrier volume and droplet size. The effectiveness of ground applications can also be influenced by speed and boom height. Applications with recommended boom height for the spray tips used will improve canopy penetration. Using a coarser spray droplet is often beneficial if carrier volume is less than optimum and ground speed is faster than optimum.
- Extension Recommendations — Contact Extension for the latest updates.
- Establish Networking — Knowing what is working for others will help fine tune your plans. Adjustments should be made as the conditions of the crop and the weather changes.
The quantity and quality of the crop is as good as it will ever be before it leaves the field. Our goal with a harvest aid program is to preserve yield and fiber quality.
GET THE NEWSLETTER TODAY!
