There have been several blight warnings recently and it is important not to stretch spray intervals at this critical time. Although a fair bit of land has been sprayed off in preparation to reseed very little seed has actually been sown. Hopefully September will provide the opportunity to catch up.
Preparing To Reseed
Livestock farmers have begun preparation for reseeding. The average grazing ley in Northern Ireland is kept down for 10 years. By this time the sward will contain approximately 50% of weed grasses which are lower yielding, of inferior quality, and will be significantly less responsive to fertilizer. Reseeding creates the best opportunity to introduce clover into the sward. The best start to any reseed is good destruction of the existing sward. This Provides good control of deep-rooted perennial weeds and grasses allowing easier ploughing.Burning off will provide a clean start for new seed whilst making weed control in the new ley easier. Choose a glyphosate based weed killer for best results, as only glyphosate will completely kill deep-rooted grasses and perennial weeds. Roundup Energy is rainfast quicker than ordinary glyphosate formulations and has the fastest turn around for cultivations.A period of at least three weeks regrowth after cutting should be left before spraying the sward. Weeds must be actively growing and the correct water volume must be used. To increase utilization of the old pasture plan to graze or cut 1 week after spraying.
Grassland Weed Control
Ragwort is appearing in many grass situations at present and is becoming a greater problem especially in lower fertility situations; it is an ‘injurious weed’ and is not permitted to grow unchecked. Ragwort is a biennial plant i.e. it grows from seed the first season to produce a rosette plant and then the following season it will produce a flowering stem, produce seed then die. Ragwort contains alkaloids which are poisonous to all livestock. Each plant can produce up to 150,000 seed with a 70% germination rate and seeds can remain dormant in the soil for up to 20 years. Treatment of plants, which are at the rosette stage now, can be very effective and an autumn application allows a check on the efficacy of the treatment to be made in early spring before allocating fields for silage or hay. Autumn is a good time to spray as the grass growth slows down and grass utilization and withdrawal periods are not as critical as they can be in the spring time when stock are turned out. Whilst ragwort is unpalatable when it is green it becomes extremely palatable once sprayed. It is important to remove as much of the root as possible; ragwort can regenerate like docks from its root fragments. A single application of weed killer is unlikely to completely eliminate a ragwort infestation due to overlapping generations of the weed. A follow up treatment should be made in the spring.
Docks are a particular problem in intensively managed grassland, especially where seeds are spread through slurry applications or poaching has occurred. Docks look unsightly, but more importantly, can reduce the grass yield and productivity. Early autumn is often overlooked as a potential time to achieve effective dock control. At this time the dock plant will revert back to vegetative growth. During vegetative growth the plant food being produced in the leaf is moved into the root for storage. Translocated herbicides are moved through the plant along with the food, hence if they are applied at this stage more product will end up in the root giving better root control.
Where clover is not considered important sprays based on the chemicals fluroxypyr, triclopyr or dicamba/mecoprop mixtures should be used. If clovers are an important component of the sward Squire may be used .Remember in most circumstances treatment is most effective where a second application takes place within a 12 month period.
Chickweed is an annual weed and seeds will germinate at any time of year but particularly in autumn when growing without competition from other plants. Common chickweed can produce approximately 800 seeds and it takes 7 to 8 years for the seed bank (supply of viable seeds in soil) to be 95% depleted, insuring an infestation for many years. Because of its ability to produce large numbers of seeds under cool temperatures, common chickweed rapidly colonizes any cool, moist area before winter or spring crops can become competitive.
Growers should continue to maintain fungicide protection of the haulm until the crop is harvested or the haulm is 100% desiccated. Timely desiccation is an essential part of good seed and ware production. Diquat is the most widely used farmer applied chemical desiccant .The rate of haulm desiccation is slow and therefore fungicide protection should continue after application. Even after two split applications of Reglone certain varieties of potatoes are difficult to burn off completely and be certain no regrowth will appear. Spotlight Plus is a desiccant recommended for use after a 7 day interval as a follow up T2 treatment to the T1 application of Reglone and gives complete kill of any stems remaining and stolons below the ground but it is poor on leaves.
Pre-Harvest Weed Control
Early sown Winter Wheat and Spring Barley crops should be examined to decide whether or not they require pre-harvest treatment for the control of annual and perennial weeds especially scutch, rough stalked meadow grass and thistles.
Roundup Energy is the most effective and consistent product for this treatment. It is a complete product that does not require additional wetter to be effective, even at low rates.
Roundup Energy should be applied when the grain moisture is below 30% which coincides with the hard dough development stage (GS 87). The safe stage is 1-3 weeks prior to harvest leaving at least 7 days between spraying and harvesting.
Pre-harvest Round-up not only controls weeds but also helps to accelerate senescence of the crop making the harvest earlier, combining easier, and reducing drying costs.
Pests in Grain
To ensure this season’s crops remain free from pests, stores need to be thoroughly cleaned of any old grain that may be harbouring pests. As pests arise from within the store and not the actual newly harvested crop it is essential to clean the store and associated machinery. An insecticide such as Reldan may have to be applied. Ideally once the grain has been harvested, the moisture content should be reduced to 14% or lower. This is the key value above which grain pests such as mites, beetles and weevils can breed and survive.