Stem canker agar

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Contents 1 Purpose 2 Ingredients 2.1 Table 1 2.2 Table 2 3 Instructions 4 Notes 5 References 6 Contributed by

Purpose

This semi-selective media will inhibit all non-"Southern DPC" Phomopsis isolates and slow down most other soybean fungi. Often used for the isolation of Diaporthe from soybean.

Ingredients

Table 1

Ingredient
PDA	39 g
H2O	1 L

Table 2

Ingredient	g product/l	a.i./l
Bayleton 50 WP	.05 (.1 g)	.025g/.050g
Botran 75 WP	.001 g	.00075 g
Vitavax 75 WP	.002 g	.0015 g
Apron 50 WP (Metalaxyl)	.031 g	.0015 g
Lactic acid 85%	1.7 (2.0) ml

Instructions

1. Mix ingredients from table 1, autoclave and cool to 50°C
2. Add ingredients from table 2, stirring constantly while pouring.

Notes

• “Southern DPC” grows at about ½ speed and has a distinctive feathery colony margin.
• If you use 50mg (a.i.) of Bayleton “Southern DPC” grows at about ¼ speed and other Phomopsis types don’t grow at all.
• For isolation I prefer the 25mg form because the DPC grows out quicker.

References

Contributed by

Contributed by Sherrie Smith, the University of Arkansas.