Research
Melcast results for 2003

---

Muscatine Island Research Station (Fruitland, IA)

The Melcast disease-warning system with SkyBit data directed only one spray after the initial spray; it directed no sprays with the on-site or model-corrected SkyBit data.  Scheduled spray treatments called for four to eight sprays, compared with the two-week and weekly sprayed control, respectively.  The unsprayed control and the plots treated with the two low-risk fungicides had significantly higher disease than any of the chlorothalonil-sprayed treatments.  The final percent symptomatic foliage was approximately equal in all of the treatments, and was fairly low in all treatments, due to prolonged dry weather in August and early September.  Marketable weight and number of melons was approximately equal for all treatments. Overall, the Melcast system saved a significant number of sprays without an increase in foliar damage or a decrease in yield.

	Rate	Spray	Number of	%	# of marketable	Marketable
Treatment	per A	frequency	Sprays	Disease	melons (/ plot) z	Yield (lb/plot) z
Non-treated control	---	---	0	27.0 a	10.2 ab	40.2 c
Bravo Ultrex 82.5WG	1.8 lb	Melcast y	1	8.4 b	10.5 ab	49.8 ab
Bravo Ultrex 82.5WG	1.8 lb	Melcast x	2	4.3 b	10.0 ab	43.7 bc
Bravo Ultrex 82.5WG	1.8 lb	Melcast w	1	13.8 ab	9.5 b	43.2 bc
Serenade WP	8.0 lb	7-day	9	25.1 a	10.0 ab	43.9 bc
Kaligreen 82 WP	4.0 lb	7-day	9	24.7 a	11.2 ab	48.2 abc
Bravo Ultrex 82.5WG	1.8 lb	7-day	9	1.0 b	12.0 a	49.1 abc
Bravo Ultrex 82.5WG	1.8 lb	14-day	5	1.5 b	11.5 ab	53.8 a
LSD (0.05)v				19.0	2.1	9.5

^z Values calculated from four 25-ft. plots  
^y Using on-site weather data
^x Using SkyBit weather estimates
^w Using corrected SkyBit weather estimates modified with CART (Kim, K.-S. et al., Plant Disease 86:179-185).
^v Means followed by identical letter are not statistically different according to Fisher's protected least significant difference when P=0.05.