Comparing Acala Defoliation Timings with Yield and Quality

Abstract

Chemical defoliation is a necessary pre‐harvest practice in cotton (Gossypium hirsutum L.) production in California, and all harvest aid efforts require proper timing to preserve cotton lint yield and quality. Generally, cotton growers are advised to begin defoliation as early as possible, but not so early that they cause yield and quality loss. In order to have confidence in this final pre‐harvest step, growers monitor the growth stage of their crop by counting the number of nodes above cracked boll (NACB). In California, it is common practice to apply the first defoliant treatment at 4 NACB, which corresponds with the US Cotton Belt's recommended timing, which is when 60% of the harvestable bolls are open (9,20). It can be beneficial to have an early defoliant application because often it leads to an earlier harvest. This early harvest allows cotton growers to conduct their harvest prior to the onset of adverse late‐season fog or rains that can occur in California's San Joaquin Valley and make harvests more difficult. The objective of this research on San Joaquin Valley Acala cotton was to compare the impact of different rates of Ginstar (thidiazuron/diuron) or Ginstar plus Finish (ethephon/cyclanilide) on defoliation, yield, and fiber quality of cotton when defoliant applications were initiated at the earlier 6 NACB timing, which corresponds to 40% open boll versus the common 4 NACB timing. Starting the defoliation process with an Acala cultivar at 6 NACB instead of at 4 NACB did not significantly affect yield or cotton HVI (high volume instrument) fiber quality characteristics. Earlier defoliation could be of significant benefit in years when later‐maturing crops or worsening harvest‐season weather necessitate the initiation of an earlier harvest.

Effects of Dosage and Spraying Volume on Cotton Defoliants Efficacy: A Case Study Based on Application of Unmanned Aerial Vehicles

“…The thick canopy and weather condition have a greater impact on defoliation and boll opening [35]. Defoliants like thidiazuron/diuron and ethephon/cyclanilide have optimal activity when maximum and minimum daily temperatures are above 27 • C degrees and above 10 • C, respectively [6]. However, in the northern areas of Xinjiang, where the cotton has a relatively short growth period and the temperature cool down soon in September.…”

“…Defoliant application timing has a significant effect on cotton yield and quality [5][6][7]13]. However, there are few reports on the effects of defoliant dosage on cotton yield and quality.…”

“…Defoliation or leaf abscission is induced in cotton as a natural physiological process, which is usually inadequate or not timely enough for a complete mechanical harvest of cotton. Therefore, defoliation before harvest is often induced by managing the plants so that senescence, abscission (separation) layer development and leaf drop are encouraged [4][5][6][7]. Advantages associated with defoliant application prior to cotton harvest include: increased harvester efficiency, reduction in the leaves and trash content in harvested lint, and quicker drying of dew.…”

İKİNCİ ÜRÜN PAMUKTA (Gossypium hirsutum L.) YAPRAK DÖKTÜRÜCÜ KİMYASALLARIN VERİM VE KALİTE ÖZELLİKLERİ ÜZERİNE ETKİSİ

“…Denememizden elde edilen değerlerin yüksek çıkmasının nedeninin, hasadın geç y a p ı l m a s ı n d a n d o l a y ı k a y n a k l a n d ı ğ ı düşünülmektedir. Wright et al (2014) çalışmadan elde ettiği değerler, 2009 yılında erken defoliant uygulama zamanında lif sarılık derecesi 11.9, geç uygulama zamanında ise 11.7-12.0 arasında değiştiği ve 2010 yılında ise 12.0-12.2 arasında, geç uygulama zamanında ise 12.1-12.8 arasında değiştiği belirtilmiş ve bizim değerlerimizle uyum sağlamamıştır.…”

The Effect of Different Harvest Aiding Chemicals on Yield and Yield Components of Cotton (Gossypium Hirsutum L.)

“…Defoliant timing has also a significant influence on the fiber quality. Too early or too late defoliation affects the fiber quality adversely (Samani et al, 1999;Wright et al, 2014). Early defoliation can be critical for maximum yield.…”