Crop Crack

The cereal acreage in the ground to date  is the highest seen for some time but the  recent heavy rainfall has slowed down winter wheat drilling and autumn herbicide application.  Slug populations were high throughout the summer and remain so, posing a threat to all crops especially with the current mild damp conditions.  Early drilling of winter wheat dramatically increases the risk of take-all following cereal situations. Therefore a seed treatment is advisable.  BYDV is a disease carried by aphids and passed into the crop when they feed on the young plants as they emerge through the ground – once infected the disease cannot be controlled.  Grassy stubbles and volunteer cereal plants act as host plants for aphids.  If a seed treatment has not been applied an application of Sumi-Alpha should be applied from the two leaf stage of the crop.

Annual meadow grass is the main target weed in NI as this weed is the most damaging to yield in all cereal crops. The key to good herbicide control is early timing –  before or soon after emergence of the crop.  This season with the dry warm conditions pre-em products have not performed as well as expected.  Residual herbicide product persistency depends very much on damp soils and cooler temperatures. Scorch has also been an issue with high soil and air temperatures in some crops this autumn.

The last two seasons have enabled us to learn more about the autumn herbicides when used beyond their recommended timing.  After two very wet autumns, much of the flufenacet in CRYSTAL and chlortoluron(CTU) in BUCKLER was applied well after the optimum timing. Crystal applied onto barley crops at the 3-4 lt rate per ha performed extremely well on well tillered annual meadow grass (AMG).  The inclusion of BUCKLER in the mix will control larger AMG but there is varietal restriction.  Sempra has been widely used this autumn in mix with Crystal to strengthen the spectrum of BLW control where weeds are through the ground.  Most of the herbicides that are effective on AMG are not safe on oats, making grass weed control in this crop particularly difficult.  In recent years LEXUS CLASS has been the principle product used and does a reasonable job when conditions and timings are optimal.  SUMIMAX is now another alternative but is an off label approval(EAMU) for use on winter oats.  It gives improved AMG activity over LEXUS CLASS and has excellent broad spectrum BLW activity including groundsel and fumitory but must be used pre-emergence of the crop.  Othello will be widely used again this spring onto winter wheat crops. In known deficient soils, manganese should be applied during November. Treatment of the condition before deficiency symptoms are seen will mean stronger healthier plants going through to spring.

There have been several blight warnings recently and it is important not to stretch spray intervals at this critical time. A fair acreage of land has been reseeded this season and combines have been busy in many areas over recent weeks but this week it has been a bit stop start.  I would urge all farmers to assess both land intended for reseeding and winter cereals to monitor for slugs as numbers are greater than they have been for some years.  Treated seed is a priority if slugs are present. I would like to impress on you the need to carry out soil samples at this time to ensure all nutrients will be readily available to the growing crop.

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 except sheep. 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. Forefrot gives the most reliable control of ragwort, or alternatively,  Lupo + Fortune wetter also shows useful activity

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 Ultra 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.

Potatoes

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.

The drought during July has caused rapid senescence on many winter wheat and spring barley crops. Some winter wheat crops have been harvested. In order to ensure harvested crops are kept free from pests,stores need to be thoroughly cleaned to ensure any debris that may be harbouring pests is removed.Pests arise from within the store and not from harvested grain.  Reldan 22 can be applied to empty stores to combat grain store pests.

Autumn planning

The heavy rainfall will bring slugs back up onto the soil surface and there will certainly be a need to assess numbers for autumn planting.   An easy way to trap is to use dry food such as breakfast cereal (muesli) or similar and place a tablespoon under a slate or fertiliser bag.  Traps should be checked early in the morning approximately two days after being placed in the field.  Slugs don’t like fine firm seedbeds so good cultivation can reduce the risk of damage as can deeper sowing. There are also some cereal seed treatments which can protect seed hollowing by slugs but damage to shoots remain a threat.  BYDV and wireworm protection can be given in seed treatment as well as take-all and autumn foliar diseases.

Potatoes

The risk of blight remains high with great variations in particular areas due to localised showers.  To try and keep crops free from blight where pressure is severe requires short intervals appropriate for high risk and also the use of fungicide products with curative activity.  Fungicides with good rainfastness will be very beneficial given the current spells of heavy rain, especially because it’s been difficult to accurately predict the timing and location of showers.

Propionic Acid

Propionic acid has an energy value of 1.5 times that of barley so as well as preserving the grain it also adds to its energy value. With Propionic treatment, harvesting can take place when there is still surface dampness on the grain, dew or rain. Harvesting can start earlier in the morning or after rain and continue later at night, giving a quicker more flexible harvest, which leaves extra time for autumn cultivations. By harvesting before grain is fully ‘ripe’ a higher yield is also obtained, reduced shedding losses may save 200kg per hectare.

Natural vitamin E levels in moist grain, whether treated or not, are destroyed during storage. When moist grain forms a major part of the diet a mineral/vitamin supplement high in vitamin E should be used.

Treated grain can be stored simply on a dry floor. It should not be stored with untreated grain.

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