Root vegetables like carrots, potatoes, and onions have specific rotation, cultivation, pest and disease, and harvesting requirements. Carrots are sown thinly in drills and thinned, needing regular watering. Pests include carrot fly and viruses spread by aphids. Potatoes are planted in early spring and earthed up, with slugs and blight as pests. Sweetcorn is grown in blocks after manuring land the previous autumn, and risks birds and corn smut without rotation.

1. RHS Level 2 Certificate Week 22 – Outdoor food production. Vegetables – root vegetables and miscellaneous

2. Learning Outcomes 1. Vegetable production 1. Root vegetables. For named varieties of each of carrots (early and main crop), potatoes (early and main crop) and onions (spring, main crop and over wintering), state: 1.1 state the place in seasonal rotation and sucessional cropping 1.2 state cultivation, propagation and care requirements 1.3 state 2 pests and 2 diseases and their control 1.4 state harvesting period and technique and storage 2. Miscellaneous veg. For named varieties of sweetcorn, state: 2.1 state the place in seasonal rotation and sucessional cropping 2.2 state cultivation, propagation and care requirements 2.3 state 2 pests and 2 diseases and their control 2.4 state harvesting period and technique and storage [ NB – start exam revision this week]

3. Root vegetables – general points Root vegetables are discussed together but have particular and differing requirements. Generally, apart from carrots, manure is applied when digging the plot the previous autumn. Use a stale seed bed and apply a balanced fertilizer when preparing this. Lime requirements vary depending on the crop. Watering is important and should be consistent – lack of water leads to split roots.

4. Carrots ( Daucus carota ) Varieties Round rooted – good for heavy or stony soil. E.g. ‘Parmex’ , ‘Paris Market’ Early – ‘Amsterdam Forcing’ Main Crop: ‘Chantenay’ Late Main Crop: ‘Autumn King’ Resistant to Carrot Root Fly: ‘Resistafly F1’

5. Carrots - cultivation Dig the soil in Autumn but do not manure or add compost. Prepare a stale seed bed, adding balanced fertilizer but do not lime. Sow where they are to grow, carrots resent transplantation. Sow in 1cm deep drills about 15cm apart, very thinly to avoid the need to thin.

6. Carrots – after care Water regularly after germination. Irregular watering causes split roots. Thin if necessary to 4-6cm apart. On a damp overcast day and remove all thinnings. Keep weeds under control until well established. Use a mulch between the rows. Control pests and diseases.

7. Carrots – pests and diseases Carrot root fly – low flying insect lays eggs in the soil and crowns of plants. Control – barriers of fine mesh, nematode control available. Good crop hygiene at harvest. Aphids – spread viruses so control by using fatty acid spray as soon as they are seen Violet root rot – no control, apart from long rotation and crop hygiene. Dwarf Motley virus – discoloured leaves and poor yield. Spread by aphids so control is to control aphids.

8. Potatoes ( Solanum tuberosum ) Varieties Early: ‘Pentland Javelin’ Good disease resistance and some resistance to eel worm Salad: ‘Pink Fir Apple’ Good flavour and unusual appearance, smaller yields than traditional varieties Main Crop: ‘Cara’. Good blight resistance.

9. Potatoes – cultivation (1) Dig and manure the previous Autumn. Chit the seed potatoes before planting to avoid rotting off in the soil. Plant only certified virus free seed potatoes. Prepare a stale seed bed and apply balanced fertilizer. Do not lime. Early varieties – plant in March, main crop in April (provide frost protection on cold nights) Water regularly at the base of the plants.

10. Potatoes – cultivation (2) Earth up when haulms are about 30cm tall to half their height. Prevents spuds turning green and encourages tuber formation. Main Crop varieties benefit from high nitrogen and potash feed when the canopy begins to touch. No need to feed Early varieties.

11. Potatoes - harvest Harvest Early potatoes once they have flowered. They should be chicken egg sized. Earlies do not store well. Treat Salad varieties as for Earlies. Main Crop – harvest once the haulms are dieing back (but do not leave too long because of late blight). Lift and allow to dry before storing in a cool, dark, dry place.

12. Potatoes – pests Slugs – soil dwelling Keeled Slugs so pellets of limited use. Good cultivation and use nematode control. Wire Worm – avoid planting on newly converted grassland. Use traps and cultivate soil well to expose the pest. Adjust planting times.

13. Potatoes - diseases Blight – brown patches on leaves, dark spots on tubers which then rot. Grow resistant varieties, spray if necessary with copper fungicide or Dithane. Avoid splashing the leaves of the plants when watering. Mosaic virus – yellow mottled leaves, weak plants and poor yield. Control the aphid that spread the virus.

14. Sweet Corn - varieties ‘First of All’ early and cold resistant, cobs about 12cm long. ‘Minor’ A miniature corn for stir frying or steaming whole. Pick at about 6-8cm long.

15. Sweet Corn cultivation Not in a rotation group but rotation can help to control Corn Smut Dig and manure the previous Autumn. Use a stale seed bed, incorporate a balanced fertilizer but do not lime. Sow in modules under glass in April or where they are to grow in late May/June. Plant or sow in blocks at 45cm centres.

16. Sweet Corn – after care Water well in dry weather, additional irrigation gives most benefit when the cobs are developing. Keep weeds under control, particularly when plants are young. Feed with liquid feed (high potash) when cobs start to form. Harvest when the silks turn brown and the grains give a milky juice if squeezed.

17. Sweet Corn – pests and diseases Birds – threat to seedlings. Use netting to protect crop. Frit Fly – tunnel the growing tips. Chemical control available if this is a problem. Corn Smut – produces galls which should be removed and burnt before they release spores. Rotation can control.

18. Learning outcomes 1. Vegetable production 1. Root vegetables. For named varieties of each of carrots (early and main crop), potatoes (early and main crop) and onions (spring, main crop and over wintering), state: 1.1 state the place in seasonal rotation and sucessional cropping 1.2 state cultivation, propagation and care requirements 1.3 state 2 pests and 2 diseases and their control 1.4 state harvesting period and technique and storage 2. Miscellaneous veg. For named varieties of sweetcorn, state: 2.1 state the place in seasonal rotation and sucessional cropping 2.2 state cultivation, propagation and care requirements 2.3 state 2 pests and 2 diseases and their control 2.4 state harvesting period and technique and storage [ NB – start exam revision this week]