In autumn, the foundations of the harvest are laid on half of our arable land.
It is therefore very important not to close the season after sowing and postpone crop care until spring, but to watch and monitor the development of all the fields we have gone to the trouble and expense of sowing.
1. Rapeseed care
This is the crop that needs the most observation. In all the years of drought and slush, difficult germination or lush development, we should by now be used to visiting the rape crop every 2 days. It is desirable to place the yellow containers at the edges of the fields after sowing rapeseed. The rainfall has been very unevenly distributed in the different regions this year (and not only this year), so we have crops from the emergence stage, up to the 8 leaf stage now. Both are equally dangerous conditions for mid-October. If it gets cold and dry - bad luck for the small crops, if the weather is wet and warm - big risk for the strong rape crops. Therefore, we diagnose each field separately and carry out the measures according to phase and need.
a/ soil crust
One under-appreciated measure is the rotation of germinating oilseed rape crops to break up the soil crust where it exists. The best tools are rotary hoes or harrows (hedgehogs, passive tillers) or in a pinch ordinary light tine harrows where they are still available. Rotary harrowing is done at high speed diagonally across the crop, thus breaking the bark and allowing air into the soil, which aids the germination or development of plants that have already emerged. The bark is also capable of breaking or pulling the taproot of 3-4 leaved canola plants and destroying them. The rototilling itself may pull out individual plants, but the overall effect is rapid and highly positive.
b/ enemies
Almost everywhere insecticide has already been imported. In places there was no threshold of economic harm to any pest, and in places there was infestation by fleas, wasps and cabbage butterflies or nightshades at the same time. The latter two pests are often underestimated, but on land where there is also vegetable production and greenhouses, the caterpillars of these butterflies can chew up incredibly large areas of oilseed rape crops in a matter of days - such rapid and voluminous damage even a vole cannot inflict.
The wasp is very dangerous for small crops, for germinating plants. The flea can also destroy young plants, but it must be kept an eye on throughout autumn, because if you do not fight off the adult, it will lay eggs next to the root necks of the plants, the larvae will enter them and in the spring you will have "red" bases.
Economic damage threshold for flea control: 2 adults/sq m at emergence; 4 adults/sq m after 3rd leaf emergence; 3 larvae/plant. When using yellow containers - 50 adults caught in a yellow container after 3 days. The yellow containers are placed 5-6 m inside the field, not more.
Control of the rapeseed leaf wasp is carried out at an economic threshold of 2-3 numbers/ sq m of false caterpillars or 2-3 numbers/sq m of damaged plants.
Butterflies and nightshades - treat immediately at indications of caterpillars and thrips with large leaf bites.
The official list of currently authorised and registered insecticides in Bulgaria can be consulted for the means and doses of plant protection.
c/ weeds
The usual practice implies sealing after sowing with a soil herbicide, but since in practice in Bulgaria there is almost no practice of provoking after harvesting, we almost massively observe annually the emergence of many volunteers from the predecessor and this requires the application of anti-weed herbicides. The choice of products is large, but in the registered doses most of them can affect only emerging volunteers and at most up to their 3rd leaf. However, growers are waiting for more wheat to emerge and this is happening in stages of varying depths due to mistakes in treatments, with some even going as far as tillering, meaning that doses have to be increased significantly. On this point, consult specifically with the suppliers of the relevant products you have chosen.
Those who have sown Clearfield oilseed rape should not wait for all the flora in the field to germinate, Cleranda also has a partial soil action and should be applied in good time.
As for sinapis - don't be under any illusions that you can manage it vegetatively. You just need to pay more attention to the complex system of treatments and plant protection within the rotation. Large sinapis will frost, young mustard will overwinter. This also applies to other cruciferous weeds. Any product you recommend against them in conventional technology will either be ineffective or phytotoxic to canola as well.
Many other broadleaf weeds in their early stages are controlled fairly successfully with Galera Super and to some extent with Lontrel.
d/ diseases
A major disease for autumn is phoma. Do not leave plants unprotected against it before winter. If the infection enters the root collar, the consequences in spring are fatal. Fungicides against it are also growth regulators and stop the growth of the central stem, thus guaranteeing a more successful overwintering.
Occasionally there is also an attack of powdery mildew on oilseed rape, but targeted control in autumn is not necessary.
e/ feeding
Boron is a must. In autumn at a dose of 15-20 g/dcaa mandatory. Zinc is another element that works well on oilseed rape for its development, crop homogenisation and overwintering.
The weakest crops should also be fed with granular fertilizers - ammonium nitrate or NPK (complex fertilizer), or with liquid nitrogen-containing fertilizers, but this should be done by the beginning of November, so that the crops can pull in development, but not be worn out for the winter.
2. Cereal crops
In the autumn of 2014 we could observe in some areas a calamity of wheat flies, so it is better to avoid early sowing in arable areas. Higher populations of wheat flies are also present in one-sided nitrogen fertilized crops. In any case, crops should be monitored 3 times a week for flies, for wheat runner and for voles.
With flies, the fight is against the adult. If we have missed the moment and the larvae have invaded the central leaf, insecticidal control is already pointless, but it is imperative to apply a foliar fertiliser containing nitrogen and the trace elements manganese, zinc and copper, so that the plants will strengthen, strengthen their development and overcome the damage caused by the larvae in the central leaf by compensating from the lateral ones. This is also why varieties that have a stronger sibling ability suffer less from grain fly damage. The economic damage thresholds for Hessian and Swedish flies are 50-60 adults per 100 entomologically bagged swaths, and for the wheat runner, 1 larva per square meter. Zabrus tenebrioides is a very insidious pest, so any patch appearing in the crop in autumn and early spring should be immediately examined and if not from a vole, a second causal agent should be looked for as runner - characteristically ground-up dribble-like plants that turn yellow and die. It can also cause damage under snow cover.
What has been striking in recent years is that the vole does not start its invasion with colonies at the edge of the field, but makes its 'homes' increasingly
inwards, thus remaining less visible for a long time. I always recommend that regardless of the crop, the field should be circled and observed length and breadth, not just viewed from the edge. The tracks from a tractor or jeep won't do as much damage as the damage found late.
To control voles, it is important to place baits in nearby alfalfa crops in early fall, and to plow those old alfalfa crops that will spoil as early as possible in the fall, as they are traditionally a large "reservoir" for field mice. Mice usually choose their food in the following order: alfalfa - rapeseed - barley - wheat.
Of the diseases, the most insidious in autumn are leaf septoriosis and net blotch. These are extremely persistent diseases and recur constantly. Recurrences should be avoided, tillage systems should be combined over the years to avoid creating a favourable environment for pathogens and larvae. It is unacceptable to surface old, undecomposed straw from the previous year, as well as piles of crop residues from the direct predecessor. Denser crops are generally more susceptible to fungal diseases. Also wet weather favours the development of powdery mildew.
Diseases in autumn are treated rather symptomatically - when characteristic manifestations of the disease appear. Of course, there are fungicides with a protective effect, but in practice in continental areas healthy crops are not treated, as winter temperatures are expected to be below freezing, which does not allow the disease-causing organisms to develop, and in early spring, after inspection, curative or prophylactic treatment is carried out when conditions are already present for their multiplication.
3. Winter legumes
Crops such as winter peas, vetches, etc. usually do not require autumn care. It is recommended to sow seeds decontaminated with a tyram-based fungicide and seal with a universal soil herbicide such as Stomp or Pendigan or others. Alternatively, if a lot of volunteers emerge, an anti-weed herbicide should be used, but as the sowing date for these crops is late - by the end of October - we usually control weeds in spring. In autumn there are no typical pests, possibly there may be an attack by native or migratory omnivorous insects.
However, legumes require a long rotation period. They should not come to the same field for a minimum of 5 years. If this is not respected, we will inevitably expect the development of diseases and soil pathogens as early as autumn.
4. Catch crops for green manuring
Catch crops or pre-crops for green manuring are sown en masse for the first year in Bulgaria. Some are overwintering, some non-overwintering. On this subject I wrote separate extensive articles. Either way, every crop is a potential host for disease and pests, so don't underestimate their monitoring and treatment either, after all they are on your land, in a field you will be cultivating in the future and you don't want to pump up the infectious and entomological background. There the fight is according to the crop and the specific pests.
For those who have seriously and professionally embraced the idea of green manuring and the advantages of cover crops, I attach a photo of a forage turnip crop of the variety Anna of Saatbau Linz, sown by the company Vardmex near the village of Vardim, municipality Svishtov.
12.10.2015 eng. Evelina Marinova
08.10.2015