Assessing direct and indirect effects of the fungicide flutriafol on arbuscular mycorrhizal fungi in controlling cotton root rot
Mason, Trevor Tarek
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Cotton production systems across the Southern High Plains employ several different methods in managing soil pathogen outbreaks including crop rotation, and fungicide treatments. Despite these approaches, disease outbreaks from cotton root rot occur often with heavy crop loss. Recently, the triazole fungicide flutriafol has been used in soil application to treat Cotton Root Rot. Flutriafol is particularly useful in that it is a very stable compound, has an easy incorporation method with a low rate of application and exhibits broad spectrum control of a variety of fungal root pathogens of cotton. However, triazoles can have determinatal impacts on saprophytic fungi, soil bacteria and arbuscular mycorrhizal symbionts of cotton. With the multiple direct and indirect effects of flutriafol application noted for both the soil microflora and crop plants, a more direct analysis of flutriafol in plant tissue and soil was needed as the current methods are expensive and time consuming. A series of procedures was developed to extract the flutriafol from soil and cotton plant roots to evaluate the efficacy and analytical capabilities of using matrix-assisted laser desorption/ionization-time of flight (MALDI-TOF) TOF 4800 plus in the positive mode for flutriafol detection. MALDI-TOF detection of a standard flutriafol formulation proved to be successful. The compound produced a distinct peak, located at 302 m/z. Efficacy trials of one-month old cotton showed that a minimum of 5.0g fresh weight of root was necessary to achieve consistent detection of flutriafol, while any amount fewer than 5.0g would require a longer extraction time of 90 minutes, compared to the normal extraction time of 50 minutes, to produce detectable limits. Using a split root system flutriafol was shown to be translocated systemically throughout the root system. While the concentration of flutriafol in plant roots is limited as observed using MALDI-TOF mass spectrometry, the procedure was able to quickly detect and quantify small amounts using only water as the extractant.