Establishment of North Face with the Bonavaree mix had been slow, and the season at Bonavaree had been one of the most problematic years to establish Lucerne and Lucerne mixes. This paddock is now coming into it’s own, and is looking good following a bit of careful management. The main issues this year were:
Cold conditions: following drilling slowed seedling establishment. Doug thinks the cold conditions were more significant to slow establishment, than the below average rainfall in November and December. “We doubt it is the dry, we’ve drilled Lucerne very successfully in far drier years than this”. Derrick confirmed “that in the presence of soil moisture – emergence of all species is then dependent on the accumulation of heat units sometimes known as growing degree days. Thus, cooler soil temperatures were the main reason for slow emergence.”
Wet conditions: Some of the wetter parts of the paddock had reduced seedling survival. This was possibly due to the disc drill glazing the furrow. The emerging radicle (root) was therefore unable to penetrate the surrounding soil, and therefore did not establish.
Pests: also played a part in reducing plant numbers. Reports from farmers and agronomists throughout Marlborough have reported increased pest damage to spring sown Lucerne paddocks. The number one culprits in Lucerne this year appear to be:
- Greasy Cut worm: this pest is characterised by it’s feeding habit of cutting plants off close to the soil surface, and therefore create more crop damage than they actually consume. Their fully grown larvae (look like catepillars) have a greasy appearance, and either live above ground feeding on plants, or burrow below the soil surface as they mature. There are many host plants of these pests in both pastures and crops (brassica and corn). Of interest to the Avery’s is that the favoured food source of greasy Cutworm is: Lucerne, clover and plantain. Docks are also favoured plants. Damage is also worst after a short fallow, in weedy fields and on leeward side of shelter. A good source of information on this pest can be found at the following websites: http://www.far.org.nz/mm_uploads/52Mz_Cutworm.pdf and http://www.hortnet.co.nz/publications/hortfacts/hf401011.htm. Fraser had got onto this pest early due to his regular crop inspections following sowing. Two sprays with Chlorpyrifos 500g/L (in this case Lorsban) appears to have reduced pest numbers and this paddock has now recovered. Some Lucerne paddocks at Bonavaree and many parts of Marlborough will require re-drilling. Summer brassica paddocks also appear to be severely damaged on some properties up here.
- Nysius fly (also called Wheat Bug): was identified by Fraser as another pest in this paddock causing seedling loss. The Nysius fly is a pest with a wide ranging number of host plants (approximately 40), from brassicas, pasture grasses and legumes and weeds. It has 2-3 generations per year; two generations occur in the South Island. It prefers hot, dry conditions where direct sunlight strikes the ground. Rain inhibits activity. The largest populations are found in the driest districts of New Zealand, and higher numbers are found in dry years such as this one. The adult fly is characterised by a silvery triangle at the tail end. And are 4 mm in length when fully grown. Immature adults are a pale green colour, and then change to the brown/grey colour shown here. Eggs are creamy white when first laid and then turn bright orange when close to hatching. The Chlorpyrifos spray used on this paddock, principally for greasy cutworm control, should also have had some impact on Nysius fly too. Spray should be applied as soon as damage is evident or when Nysius nymphs can be found feeding on seedlings.
- Springtails: these were not identified as a pest in this paddock causing seedling damage, but are common in newly sown Lucerne paddocks and can cause seedling loss. Springtails feed on the emerging shoots of seedlings, which kills the seedling outright. The damage can appear to be a poor seed strike throughout the paddock. They are small, but are underrated as a pest and are prolific in hot dry conditions. Seed treatments do not usually offer adequate protection under high pressure from springtail infestations. If paddocks are to be drilled shortly (3-5 days) after spraying out the weeds, then Lorsban (Chlorpyrifos) can be added to Glyphosate. Otherwise it can be sprayed on its own 1-2 days before crop emergence.
The paddock is now looking healthy post spray and has filled in. Even with some reduction in seedling numbers the plant population looks to be sufficient for a well established permanent pasture (see photos below, photos taken on 18th December 2012). Pasture height was approximately 22 cm. Although the plantain looked to be slightly wilted (see top right photo below) this was probably due to the warm windy conditions at the time. There seems to be little effect of the dry conditions on dry matter production at this stage.
The plans for this paddock are as follows:
- If it rains then a light graze with sheep will occur in January, although will depend on dry matter response or pasture height. And then shut up for seed set of all species.
- If it doesn’t rain then the paddock will be shut up to allow reseeding of all species. With grazing to occur post seeding.
Key Bonavaree messages:
Always monitor your newly sown paddocks, at least every 3 days. Get onto problems early.
Don’t think that treated seed will always protect seedlings, further treatment with sprays post sowing maybe necessary.
Know what you are dealing with. Get pests identified, and use the right control measures.
Be aware of pest lifecycles and host plants and use management techniques to control pest numbers during the year before they cause damage.
Remember always seek advice from your local ag-chem expert as to chemical choice, and rate according to your own situation.