Carolina Cotton Notes - August 31, 2006

It is still a little too early to say what products may be needed for any given field at this point. Some of the early cotton in dry area may be ready soon. We have a lot of late cotton that we may need to delay defoliation until sometime in October to try to maximize yields.

There are some new products out there. Many are generic products with the same active ingredient as one of our standard defoliation products. If you have a question about a defoliant you have never heard of before, the first thing you should do is check the active ingredients and compare that to the active ingredients in the standard defoliants you are familiar with. The common chemical name for the active ingredient(s) in a defoliant is given it Cotton Information and the North Carolina Agricultural Chemicals Manual. They are also listed here in Table 3.

Resource is a new defoliant with a different active ingredient. Although the active ingredient is new it is a PPO inhibitor similar to Aim and ET. We have limited experience with Resource you can see the results from last year in Table 1. In table 2 you see Resource compared to older standards and Aim. The results with Resource look very similar to Aim in this test. We did not see a lot of desiccation in the trials last year as there was not a lot of juvenile growth at the time of defoliation. One thing we have seen in the past in rank cotton with a lot of juvenile growth is desiccation of the juvenile growth from PPO inhibitors like Aim, ET and Resource. This is usually very noticeable at 7 DAT but the desiccation tends to be transient and the plots usually look good at 14 DAT. The PPO inhibitors are sometimes used in a two step defoliation in some states that tend to have more juvenile or excessive growth. These two step application methods have worked well in research here but in most case did not improve a one step application enough to make the second application worthwhile.

Table 1. Resource defoliation test in 2006

Spray vol: 15/gal/ac			Mix Size: 3 gallons (min .52314)
Trt No.	Treatment Name	Form Conc	Form Type	Rate	Rate Unit	% Defoliation 14 DAT	% Desiccation 14 DAT	% Open 14 DAT	% Terminal Regrowth 21 DAT	% Basal Regrowth 21 DAT
1	Resource	10.0	EC	4	fl oz/a	74.25 c	6.75 a	88.5 bc	23.75 b	35 b
	Prep	6	SL	20.8	fl oz/a
	Crop Oil Conc		L	16	fl oz/a
2	Resource	10.1	EC	4	fl oz/a	88.25 ab	6.25 a	92.5 a	2.75 cd	16.25 cd
	Prep	6	SL	20.8	fl oz/a
	Induce (NIS)		L	0.25	% v/v
3	Resource	10.1	EC	4	fl oz/a	88.75 ab	27.5 a	93.25 a	1.25d	18 cd
	Finish 6 Pro	6	SL	21.3	fl oz/a
	Induce (NIS)		L	0.25	% v/v
4	Resource	10.1	EC	6	fl oz/a	86.75 ab	8.25 a	93 a	6 cd	16.5 cd
	Prep	6	SL	20.8	fl oz/a
	Crop Oil Conc		L	16	fl oz/a
5	Resource	10.1	EC	6	fl oz/a	83.75 b	8.25 a	91.25 ab	8.5 c	21.75 c
	Prep	6	SL	20.8	fl oz/a
	Induce (NIS)		L	0.25	% v/v
6	Resource	10.1	EC	6	fl oz/a	92.5 a	9.25 a	93.75 a	0 d	11.75 d
	Finish 6 Pro	6	SC	21.3	fl oz/a
	Induce (NIS)		L	0.25	% v/v
7	Untreated Control					38.75 d	0 a	86 c	45 a	47.5 a
	LSD					6.791	19.929	2.903	6.618	9.241

Table 2. Beltwide defoliation test, 2006.

Rating Date Type		% Open 7 DAT	% Def 7 DAT	% Desiccation 7 DAT	% Open 14 DAT	% Def 14 DAT	% Desiccation 14 DAT
Rating Date		1/Oct/2004	1/Oct/2004	1/Oct/2004	7/Oct/2004	7/Oct/2004	7/Oct/2004
Trt No.	Treatment Name	1	2	3	4	5	6
1	Untreated	21.25 c	30.00 c	0.00 a	15.00 d	32.50 c	0.00 b
2	Tribufos	83.00 ab	86.50 ab	0.00 a	92.00 a	93.50 a	0.25 b
	Ethephon						0.00 b
	Thidiazuron
3	Dimethipin	85.25 ab	89.25 a	0.00 a	81.50 bc	87.75 ab	0.00 b
	Tribufos
	Ethephon
	Agridex
4	Thidiazuron	73.00 b	77.75 b	0.00 a	84.50 b	89.00 ab	0.00 b
	Ethephon
5	Tribufos	80.50 ab	85.00 ab	0.00 a	77.25 c	83.75 b	0.00 b
	Ethephon
6	Aim	82.75 ab	85.25 ab	85.25 ab	93.75 a	95.75 a	1.50 a
	Ethephon
	Thidiazuron
	80/20 NIS
	Aim
	Agridex
7	Resource	87.00 a	88.75 ab	11.180	93.50 a	95.50 a	1.75 a
	Prep
	Agridex
	Resource
	Agridex
	LSD (P=.05)	13.298	11.180	0.842	6.367	8.231	0.842

Table 3. Active ingredients in some commonly used defoliants.

Defoliant	Active Ingredient 1	Active Ingredient 2*
Accelerate	endothal
Aim	carfentrazone
CottonQuik	ethephon	AMADS
Cyclone	paraquat dichloride
Def	tribufos
Dropp	thidiazuron
ET	pyraflufen
Finish	ethephon
Free Fall	thidiazuron
Ginstar	thidiazuron	diuron
Harvade	dimethipin
Klean-Pik	thidaizuron
Leaf-all	Dodium cacodylate	cacodylic
Leafless	dimethipin	thidiazuron
Prep	ethephon

*Second active ingredient given for defoliants with more than one active ingredient.

MFX is a 2 lb/gal active foam of ethephon that will be available this year.
FirstPick is a new form of CottonQuik. Data on FirstPick will appear in the next Carolina Cotton Note.