Technical
“The basic aim of the research was to determine conclusively if phosphite treatments reduce Microdochium nivale infection”
If you had mentioned the word phosphite seven or eight years ago you would probably have been met with a blank stare, which is what I gave when first hearing about it in 2005. However, since then, phosphite has become very much a buzzword and much has been said and claimed for it.
John Dempsey, Course Superintendent at the Curragh Golf Club in County Kildare, has been conducting his own trials and, in this article, explains the method and the results to date
Phosphite
What’s all the fuzz about?
So, what is phosphite, and what exactly can it do for turfgrasses?
Phosphorous is a major plant nutrient - the P in NPK - which, in plants, is taken up and used in the form of phosphate (PO4
).
Phosphite is very similar chemically to phosphate -its chemical formulation is PO3
Phosphate - PO4
- only one molecule of oxygen difference. However, where phosphate is vital for numerous metabolic processes in the plant, phosphite, because of its molecular shape, cannot be utilised by plants as a source of P nutrition and, importantly, should not be applied to plants which are deficient in P.
Phosphite is derived from phosphorous acid (H2
PO4 Phosphite - PO3 106 PC FEBRUARY/MARCH 2013
), which has a pH of 2.2 and, if applied directly to plant tissues, would cause burn. So, to prevent phytotoxicity, it has to be modified prior to use with a neutralising substance, the most commonly used being potassium
hydroxide (KOH). When combined, these produce potassium phosphite (KH2
PO3
), which forms the active substance in numerous products currently marketed worldwide as either fungicides or fertilisers.
Since 2005, potassium phosphite products have been marketed in the UK and Ireland as biostimulants, or even defence activators, and are promoted as a means to reduce Microdochium nivale, the fungus which causes fusarium patch.
Microdochium nivale is an Ascomycete fungus, and the most common pathogen of turfgrass in temperate climates; it is the causal agent of fusarium patch and pink snow mould. Control of M. nivale in turfgrass is achieved by implementing Integrated Pest Management (IPM) programmes which reduce disease incidence to acceptable levels.
Chemical plant protectants are an integral part of IPM and, whilst the
Page 1 |
Page 2 |
Page 3 |
Page 4 |
Page 5 |
Page 6 |
Page 7 |
Page 8 |
Page 9 |
Page 10 |
Page 11 |
Page 12 |
Page 13 |
Page 14 |
Page 15 |
Page 16 |
Page 17 |
Page 18 |
Page 19 |
Page 20 |
Page 21 |
Page 22 |
Page 23 |
Page 24 |
Page 25 |
Page 26 |
Page 27 |
Page 28 |
Page 29 |
Page 30 |
Page 31 |
Page 32 |
Page 33 |
Page 34 |
Page 35 |
Page 36 |
Page 37 |
Page 38 |
Page 39 |
Page 40 |
Page 41 |
Page 42 |
Page 43 |
Page 44 |
Page 45 |
Page 46 |
Page 47 |
Page 48 |
Page 49 |
Page 50 |
Page 51 |
Page 52 |
Page 53 |
Page 54 |
Page 55 |
Page 56 |
Page 57 |
Page 58 |
Page 59 |
Page 60 |
Page 61 |
Page 62 |
Page 63 |
Page 64 |
Page 65 |
Page 66 |
Page 67 |
Page 68 |
Page 69 |
Page 70 |
Page 71 |
Page 72 |
Page 73 |
Page 74 |
Page 75 |
Page 76 |
Page 77 |
Page 78 |
Page 79 |
Page 80 |
Page 81 |
Page 82 |
Page 83 |
Page 84 |
Page 85 |
Page 86 |
Page 87 |
Page 88 |
Page 89 |
Page 90 |
Page 91 |
Page 92 |
Page 93 |
Page 94 |
Page 95 |
Page 96 |
Page 97 |
Page 98 |
Page 99 |
Page 100 |
Page 101 |
Page 102 |
Page 103 |
Page 104 |
Page 105 |
Page 106 |
Page 107 |
Page 108 |
Page 109 |
Page 110 |
Page 111 |
Page 112 |
Page 113 |
Page 114 |
Page 115 |
Page 116 |
Page 117 |
Page 118 |
Page 119 |
Page 120 |
Page 121 |
Page 122 |
Page 123 |
Page 124 |
Page 125 |
Page 126 |
Page 127 |
Page 128 |
Page 129 |
Page 130 |
Page 131 |
Page 132 |
Page 133 |
Page 134 |
Page 135 |
Page 136 |
Page 137 |
Page 138 |
Page 139 |
Page 140 |
Page 141 |
Page 142 |
Page 143 |
Page 144 |
Page 145 |
Page 146 |
Page 147 |
Page 148