Extracts of the brown seaweed (Ascophyllum nodosum) seem particularly effective in reducing nematode stress and it has now been shown that, following their application to plants, numerous plant genes are affected
Fig 3A Before seaweed application stress.
The severity of turfgrass symptoms will depend on the nematode species present, the nematode population sizes and, equally importantly, stress levels. Grass is adapted to coping with plant parasitic nematode feeding and, given favourable growing conditions, a significant level of nematode attack is required before observable damage appears in the plants. However, if plants are subjected to other stresses (e.g. high salinity, shade, high temperatures, drought) then the nematode population threshold above which damage is apparent will be considerably lower. So, once a nematode problem is diagnosed, what can be done? Given what we know about the interaction between nematode population levels and stress, reducing both plant stress and nematode numbers should help the situation.
Reducing plant stress
By its very nature, turfgrass is often subjected to significant levels of environmental stress. Very simple techniques can be used to alleviate this pressure, one of which is raising cutting heights. Increasing the amount of photosynthetic tissue in a golf green can quickly allow plants to recover from the effects of nematode feeding, though the demands of golfers for faster and faster playing surfaces often preclude this as a regular management option.
The use of biostimulants on turf seems to offer a more practical solution to stress
reduction in high traffic situations. Effective biostimulants include humic acid and seaweed extracts, and recent research results indicate some of the possible reasons why these materials can help turf growth and condition in the presence of biotic and abiotic stress. Extracts of the brown seaweed Ascophyllum nodosum seem particularly effective in reducing nematode stress and it has now been shown that, following their application to plants, numerous plant genes are affected, including many of those involved in coping with environmental stress. Our work in Belfast indicates that routine use of seaweed extracts or other biostimulants can significantly reduce nematode damage symptoms in virtually all turf types (Figure 3).
Reducing nematode levels
Recurring environmental problems have resulted in the loss of many fumigant and non-fumigant nematicides to both agriculture and the amenity industry. This means that traditional pesticide- based control of plant parasitic nematodes is rarely an option and turf managers must look elsewhere for a solution to high nematode levels in their pitches and greens. A number of organic soil amendments have proven useful in suppressing nematode populations in turfgrass rootzones:
Mustard brans and liquids: Brassicas, such as mustard, contain natural chemicals which break down under
Fig 3B After seaweed application
enzymatic action to release gases that can suppress plant parasitic nematodes in most soil types.
Furfural: This organic chemical, a by- product of sugar production, interacts with the nematode cuticle affecting the pest's ability to move and feed. Used at the appropriate times it can effectively suppress plant parasitic nematode populations.
Garlic extracts: Properly formulated extracts contain high levels of polysulphide chemicals containing labile sulphur-sulphur bonds that react with many enzymes in animal cells (particularly those in actively respiring tissues). Nematodes and
metamorphosing insects seem especially sensitive to the effects of some garlic extracts.
All of these materials can be effective in reducing the numbers of nematodes in the rootzone, however, their action is not systemic and nematodes inside roots are largely unaffected. This means that in the case of endoparasitic nematodes such as root knot nematodes, cyst nematodes or lesion nematodes, applications must coincide with those times when juveniles or adults are present in the rootzone.
On the following page is a case study from Shawsbridge Sports Association in Belfast. It looks at the problems caused by root knot nematodes, maintenance regimes and future plans.
97
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