Table 16. Summary of the trial design and results of monitoring soilborne pathogens from several experiments and locations in Mexico 1999.

Mega environment (ME)	Trial	Tillage	Straw management	Crop rotation	N rate (kg/ha)	Root rot incidence	Nematode incidence	Yield
ME2	201 - El Batan Rotation Trial Started in 1986 Monitored in: 98 and 99	Conventional tillage in winter Beds reshaped when needed, no tillage in spring	Winter crop residues chopped in summer Summer crop residues either retained or removed	Summer wheat Winter rape or vetch	75 and 150	Wheat No effect of tillage, straw management, and rotation. Higher incidence with 75 g/ha of N. Maize Significantly higher when residues were retained.	P. thornei numbers higher under continuous wheat than in the rotation wheat/maize or continuous maize and also higher under rape than vetch. Nonparasitic nematodes decrease in the rotation wheat/maize with burning straw compared to continuous wheat They increase under vetch with the retention of straw.	Wheat Yield of wheat is higher under 150kg/ha and in the rotation with vetch than with rape. Maize Yield not correlated with root disease symptoms.
ME2	204 - El Batan Effect of tillage, rotation and irrigation management on wheat and maize yields. Started in 1997 Monitored in: 99	Zero till Conventional tillage Irrigation with tied ridges	All crop residues retained	Winter rape or  vetch Summer wheat or maize	175	Wheat No effect of treatments. Maize Higher in conventional tillage.	Note: nematodes not measured.	Wheat Wheat yields significantly higher in conventional tillage with irrigation applied at crop establishment and following vetch. Maize Higher in conventional tillage treatments and irrigation.
ME2	ME2 - D5-El Batan Sustainability Trial Started in 1991 Monitored in: 98, 99	Conventional tillage Zero tillage	Retain Remove all	Continuous wheat Continuous maize Wheat-maize rotation	120	Wheat Root rot incidence over all the experiment was low, but significantly higher in zero tillage reatments compared to conventional tillage. Maize Root rot incidence is significantly higher in zero tillage treatments removing straw.	P. thornei numbers higher under continuous wheat than in wheat/maize rotation or continuous maize. P. thornei numbers higher in conventional tillage than in zero tillage. Nonparasitic nematodes are higher under straw retention than straw removal.	Wheat Yield was significantly higher under zero till with straw retention and more so in the rotation wheat-maize than either monoculture. Maize Straw retention under zero tillage generally increases yield and more so in the rotation wheat maize.
ME2	MV 201 - Toluca On-station management trial Started in 1994 Monitored in: 97, 98, 99	Zero or bed reshaping in summer Conventional tillage or bed reshaping in winter	In winter Wheat straw retention Wheat straw removal In summer all residues retained	Summer wheat Winter rape, vetch, or oats.	150	Wheat Higher disease incidence in treatments with zero tillage in winter and straw retention.	No P. thornei present in this site.	In 1999, no differences in yield, although yields in previous years were higher in zero tillage treatments with rape in previous cycle.
ME1	209 - Obregon Straw management for an irrigated, reduced-till bed planted o wheat, maize, and soybean system. Started in 1993 Monitored in: 99	Conventional till Permanent beds reshaped	Straw incorporated and new beds reformed after each crop Wheat and maize straw burned or left in place Wheat straw that passes throught the combine removed Wheat straw chopped and left in place; maize tover removed for fodder	Winter wheat Summer maize or soybean	0 150 300	Wheat Significantly lower on permanent beds retaining straw with 0 or 150 kg/ha of N. Maize Significantly higher incidence in conventional-tilled beds regardless of straw management. No effect of solarization observed.	P. thornei numbers higher under 150 and 300 N compared with 0 N. Nonparasitic nematodes are higher under conventional till.	Wheat The best yields were obtained in permanent beds retaining straw. Maize Yield not determined in all years.
ME1	402 - Obregon Disease status in summer maize-wheat rotation with different straw and tillage practices. Started in ? Monitored in: 99	Permanent beds Beds with conventional tillage	Straw retained straw burned With or without solarization after wheat harvest.	Winter wheat Summer maize	275	Wheat No significant differences among treatments. Maize Significantly higher incidence in conventional-tilled beds regardless of straw management. No effect of solarization observed.	P. thornei numbers higher when straw is burnt than retained. Trend for nonparasitic nematodes to be higher under conventional till (with or without straw incorporation) than permanent beds with or without straw retention.	Wheat Yields better with residue retention, but minor tillage effect. Maize Yield not determined in all years.