The occurrence of mycotoxins in barley, sorghum, teff (Eragrostis tef) and wheat from Ethiopia has been studied. Samples were analyzed for aflatoxin B(1) (AFB1), ochratoxin A (OTA), deoxynivalenol (DON), nivalenol (NIV) and zearalenone (ZEN) using high performance liquid chromatography (HPLC) and for fumonisins (FUM) using enzyme linked immunosorbent assay (ELISA). AFB1 and OTA were detected in samples of all the four crops. AFB1 was detected in 8.8% of the 352 samples analyzed at concentrations ranging from trace to 26 microg kg(-1). OTA occurred in 24.3% of 321 samples at a mean concentration of 54.1 microg kg(-1) and a maximum of 2106 microg kg(-1). DON occurred in barley, sorghum and wheat at 40-2340 microg kg(-1) with an overall incidence of 48.8% among the 84 mainly 'suspect' samples analyzed; NIV was co-analyzed with DON and was detected at 40 microg kg(-1) in a wheat sample and at 50, 380, and 490 microg kg(-1) in three sorghum samples. FUM and ZEN occurred only in sorghum samples with low frequencies at concentrations reaching 2117 and 32 microg kg(-1), respectively. The analytical results indicate higher mycotoxin contamination in sorghum, which could be related to the widespread storage of sorghum grain in underground pits leading to elevated seed moisture contents. This is the first report on the occurrence of OTA in teff.

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Winter wheat cultivar Basalt was artificially inoculated with Fusarium culmorum at the end of anthesis and treated with the systemic fungicide tebuconazole (Folicur®) a few days before and/or after inoculation. Check plots remained uninoculated and unsprayed. Head infections, yield, yield components and the percentage of Fusarium‐ infected kernels were determined. Artificial Fusarium inoculation lowered yield significantly by 24.2‐45.0%. Any fungicide treatment saved yield, thousand grain weight and kernel numbers per head. Pre‐infectional application of tebuconazole was superior to application carried out post‐infection. Moreover, the fungicide controlled deoxynivalenol (DON) synthesis in the field to a considerable extent, and enabled good control of Fusarium head blight, glume blotch and the percentage of Fusarium‐infected kernels. The levels of Fusarium kernel infection after harvest clearly reflected the DON content of w heat grain.

The t y p i c a l values and probable ranges of acid-precipitation a r e evaluated i n terms of t h e i r t h e o r e t i c a l e f f e c t s on pH and c a t i o n exchange equilibrium of s o i l s c h a r a c t e r i s t i c of t h e humid temperature region. The extent of probable change i n s o i l pH and t h e time required t o cause such a change a r e calculated f o r a range of common s o i l s . Hydrogen ion i n p u t by a c i d p r e c i p i t a t i o n i s compared t o c a t i o n inputs from n u t r i e n t cycling and o t h e r sources. For example it can be calculated t h a t 100 years of acid p r e c i p i t a t i o n (10,000 cm a t pH 4.0) could be expected t o s h i f t t h e percentage base s a t u r a t i o n i n t h e top 20 cm of a t y p i c a l midwestern f o r e s t s o i l (cation exchange capacity of 20 meq/100 g ) downward 20%, thus lowering t h e pH of t h e A 1 horizon by approximately 0.6 u n i t s , i f t h e r e a r e no countering inputs of b a s i c materials.