Given that blight can so quickly destroy an entire crop it makes sense to consider planting blight resistant varieties. Blight resistant maincrops are particularly useful – high yielding with no threat or worry that blight will take your crop! Take a look at the fantastic range available from FHF -
Vitabella is a delicious oval yellow skinned, yellow fleshed, early/second early firm potato with high blight resistance. Great storage characteristics and flavour. Superb for boiling, roasting and chips. Exclusive to Fruit Hill Farm
Connect potato is a blight resistant light yellow oval maincrop. It is becoming a main variety in organic production due to its disease resistance, eating quality, high yield and robustness.
Carolus Bestseller since 2018. Carolus potatoes are blight resistant, high yielding ánd floury with superb flavour.
Allouete Alouette is a second early variety with a red skin and yellow flesh colour that is growing in popularity. It has excellent resistance to both foliage and tuber blight.
Sevilla are a light skinned blight resistant maincrop potato. Excellent for chips! Exclusive to Fruit Hill Farm
Blue Danube The blue Sarpo. Blue Danube Potatoes have a very high resistance against tuber blight. Excellent taste.
Blight is a fungal disease caused by spores of Phytophthora infestans which are spread on the wind and which can also contaminate potato tubers in the soil. Dark brown blotches appear around leaf tips and edges, spreading towards the middle, shrivelling and rotting the leaf. The leaves and stems rapidly blacken and rot, and the plant collapses. Spores are released on the wind and quickly spread to infect neighbouring plants. Spores are also washed into the soil where they can infect potato tubers causing a red-brown rot directly beneath the skin which slowly spreads towards the centre of the tuber. Heavy rain washes the fungal spores of late blight into the soil, where it overwinters.
Infection reaches a peak during 'Smith Periods' – defined as two consecutive days when temperatures fail to dip below 10°C (50°F) and humidity remains above 90 per cent for the majority of the day. Infection in ideal conditions is almost guaranteed if the plants leaves are moist. Tubers can also be infected as the spores are washed into the soil by rain.
Best practise to avoid blight
- Plant healthy, disease-free seed potatoes from a reputable supplier.
- Grow early varieties that will be harvested before blight strikes.
- Choose an open planting site with good airflow and leave sufficient space between plants. Plant ridges in the direction of the prevailing wind. Better airflow helps the foliage to dry quickly after rain, slowing the spread of blight between plants.
- In dry weather, water plants in the morning so that any moisture on the leaves can evaporate during the day. Water at the base of the plant only.
- Take the time to properly earth up and mulch with organic matter to lock in the moisture at ground level. Extra-thick mulches, for example with straw, will give any spores dropping to the soil surface much further to travel, insulating the developing tubers against infection.
- Practise a long crop rotation.
- Manage fertility so that the plants are strong. Potatoes develop best when they have adequate potash (K) for strong growth and tuber formation. Too much nitrogen (N) will produce leaf (great for blight spores to land on) at the expense of tuber.
- Copper sprays can be applied if blight conditions have been flagged in your area. Copper acts as a fungicide and prevents blight damage to the plant. However, it is a preventative measure only and will not stop blight spreading if the potato already has blight.
- Be sure to dig up every last potato so blight has nowhere to over-winter.
- Destroy any unwanted or diseased tubers. Don’t put them on the compost heap. Remove any volunteer plants that grow from tubers left in the ground from the previous years crop.
- It is possible to save your crop if only a few plants are infected by removing the haulm from the plants. Harvesting should wait for three weeks. By this time the potatoes will have developed a thicker skin and any blight spores should have perished.