Crops Management Notes – October

October 1, 2020

CEREALS

Aphid monitoring and virus control

Once the ‘green bridge’ has been removed pre-sowing this diminishes the threat from non-winged aphids. Controlling virus carrying winged aphids is key to minimising the cereal virus risk post-emergence. Winged aphid migration is monitored by AFBI and populations are posted weekly at https://www.afbini.gov.uk/publications/cereal-aphids-weekly-results-2020. A risk forecast and advice on threshold aphid numbers, above which an aphicide application can be justified, is also published. Earliest sown cereals are at most risk as they are exposed to virus transmitting aphids for longer. Crops emerging after early November, when aphid migration starts to tail off, are a lower infection risk.

Weed control

To achieve good weed control this autumn apply residual herbicides to a reasonably fine, clod free seedbed before or soon after crop emergence, when any grasses or broad leaved weeds are still small or yet to emerge. Prioritise winter oats and barley as active ingredients, particularly those effective on grass weeds, are limited to a few products and spring herbicide options are fewer than in winter wheat. 

Slug monitoring

Continue to monitor winter crops until plants are beyond the vulnerable seedling stage. The highest risk is following rape or vegetable crops where slug numbers are high, seedbeds are cloddy and damp and seedling emergence is slow. If slug numbers exceed four per trap in cereals or one per trap in oilseed rape consider applying ferric phosphate slug pellets if emerging crops are still at risk. When using ferric phosphate, slugs often die underground, with no obvious sign of dead slugs at the soil surface. Therefore monitor closely after pellet application, looking for a decrease of feeding damage to gauge effectiveness of the treatment.

Monitoring crops in store

Continue monitoring stored grain weekly until both grain moisture and temperature have stabilised. Store pests can multiply rapidly in heated grain making early detection of increases in temperature the best way to prevent rising pest populations and grain spoilage. 

POTATOES

Minimising harvest damage

During potato harvest keep a lookout for mechanical damage to tubers. Samples submitted by Potato Business Development Group members last autumn indicated mechanical damage varied from 3 to 27%, whilst visible bruising varied from 0 to 32%. This demonstrates care taken to harvest and handle the crop carefully can give a significant lift in marketable yield. Damage most frequently occurs at drops from harvesters into boxes or trailers. Bruising is often the result of insufficient soil on the web or excess agitation. Exposed sharp edges or an incorrect share setup can cause slicing and bruising. Oversized tractor tyres running in the drill bottom or stacking overfilled boxes are two of the most common causes of crushing. Excessive damage can lead to increased problems in store and eventual down grading of produce. Early identification of damage is critical to minimise losses. To do this take a sample of the harvested crop either daily or when entering a new field, wash and inspect for damage. Hotboxing gives a quicker indication if damage has occurred.

Drying and curing

Drying potatoes quickly post-harvesting prevents the development of skin blemish diseases and soft rots. Drying within 48 hours using positive ventilation systems significantly reduces the development of diseases such as silver scurf. The curing period immediately following harvest is one of the most important storage phases. Wound healing occurs most rapidly at high temperatures and high humidity. Maintaining the crop at 12 to 15 degrees centigrade and 85 percent relative humidity for a period of about two weeks, often referred to as ‘dry curing’, allows wound healing to take place, whilst minimising the risk of disease development. Ventilating the store on dry afternoons during the curing period will normally provide adequate curing conditions. Pay particular attention to potatoes from fields where blight and soft rots are an issue at harvest. Drying and curing before grading or longer term storage is especially important in these circumstances to minimise the spread of rots through the stored crop. 

For information and guidance during the Convid-19 pandemic please refer to:

https://www.daera-ni.gov.uk/landing-pages/daera-and-covid-19