Choosing disease resistant veg varieties

Some plant diseases can be kept at bay or at least in check if we choose the right varieties. Emma Rawlings looks at the ones to grow.

It’s that time of year when vegetable diseases tend to be more prevalent. There are many reasons for this. Sometimes the plants are running out of steam and become more susceptible to disease. The warmer, humid conditions in summer benefit certain diseases and the plants may be stressed if dry at the roots. There are very few chemical controls for diseases available to gardeners even if we wanted to use them. In this issue we also have a feature by Huw Richards who recommends applying LAB to help prevent some plant diseases. Turn to page 49 to find out more about LAB and some of the diseases mentioned here.

One of the best ways to reduce disease problems is to grow varieties that have resistance to them. Here we list a few vegetable varieties that you can take note of to grow next year if you are having problems with diseases this season.

Pea ‘Ambassador’

If you have grown peas and the foliage has developed a white coating, this is likely to be powdery mildew. This variety resists this disease quite well and also fusarium, a soil-borne disease that causes the plants to turn yellow and wilt.

Cucumber ‘Passandra’

This one is best grown in a greenhouse and is an all-female variety. Powdery mildew can be a problem on cucumbers and again, as with courgettes, it can hit mid-summer and start to damage the leaves and potentially reduce cropping. This variety has some resistance to the disease.

Courgette ‘Primula’

This one is resistant to powdery mildew and types of mosaic virus. The latter can be problematic as it causes stunting, yellow mosaic patterning on the leaves which can look a bit distorted and flowering often fails. Mildew tends to hit the plants late summer and reduces the vigour, although you may have had a decent crop before it takes over.

Carrot ‘Volcano F1’

A maincrop ‘Nantes’ hybrid so a good robust one to grow. It is resistant to disease such as cavity spot (sunken lesions on the root) and crown rot disease. It is also resistant to splitting, which can sometimes be an access point for disease. Sow March to May for July to autumn harvests.

Leek ‘Porbella’

A very common problem on leeks is a fungal disease called rust and this variety shows some good resistance to it. Leek rust affects the allium family and causes orange pustules to form on the leaves. It doesn’t cause too much of a problem unless the infection is severe and then it can reduce vigour of the plants.

Clubroot on brassicas

This disease affects the roots of the brassica family so it can affect Brussels sprouts, cauliflower, cabbages, swede and turnips to name a few. Infections tend to occur in warm, moist weather so it is worse from mid-summer until late autumn. The plants will look stunted and wilt in hot weather and may develop a purplish tinge to the leaves. If you dig up an ailing plant you will see swollen, distorted roots. Liming the soil can help and also planting out quite large plants and using a little lime, mixed with soil, in the planting hole. Some varieties have good resistance to this disease such as the following.

Cabbage ‘Kilaton F1’

It took over 18 years to develop this clubroot resistant variety. It can be grown from March to May, starting off in cell trays and growing on to decent-sized plants before planting out. This variety produces good dense heads up to 2kg in weight from autumn onwards.

Late blight resistant crops

Tomatoes and potatoes are in the same family and can be devastated by this disease. See page 50 for more details. Here are a few varieties to grow to avoid damage by blight.

Calabrese ‘Monclano F1’

This forms a large tight green flower head but once this is harvested smaller flower shoots will be produced too, to give an extended harvest period. As well as resistance to clubroot it also has good resistance to downy mildew.

Potato ‘Sarpo Mira’

One of the best potatoes to grow for blight resistance. It has red tubers and is a late maincrop. These are often worst affected by late blight attacks but ‘Sarpo Mira’ will still be standing when other varieties collapse. It also has good slug resistance which is a bonus.

Tomato ‘Crimson Crush F1’

A UK-bred tomato that has excellent resistance to blight. Good-sized round red tomatoes with a good flavour. A great one to grow outdoors where blight is more of a problem than on greenhouse-grown crops.

Brussels sprout ‘Crispus F1’

A mid-season variety that has good clubroot resistance. Sow March or early April to harvest late summer through to late autumn. It is a variety that will ‘stand well’ which means once the buttons are formed you can leave the plants for some time before harvesting them if you are not ready to pick.

Potato ‘Setanta’

Another red-skinned maincrop that has an excellent flavour and is perfect for roasting, baking and making chips. The foliage may show blight damage but it doesn’t appear to affect the tubers as much as other vulnerable varieties. It is also drought tolerant and resistant to common scab and with thick skins it deters slugs too.

Tomato ‘Lizzano F1’

One of the first blight tolerant cherry fruited tomatoes and produces large harvests. It is ideally grown as a bush so it’s not one you need to take sideshoots off. Let it sprawl and do its thing. Great in large baskets and patio containers.

Cauliflower ‘Clapton’ F1’

The first cauli to have this good resistance to clubroot. It produces good flavoured white dense heads. It can be sown March to June and will then produce a harvest from late summer to late autumn.

Also try swede ‘Marion’, kale ‘Tall Green Curled’, cabbage ‘Kilaxy’.

Other varieties to try

• Parsnip ‘Picador’ (Resistance: canker)
• Onion ‘Santero’ (Resistance: downy mildew)
• Dwarf bean ‘Stanley’ (Resistance: halo blight and antracnose)
• Cabbage ‘Sarmash F1’ (Resistance: white blister disease)
• Carrot ‘Eskimo’ (Resistance: cold up to minus 10 degrees, high cavity spot, alternaria)
• Tomato ‘Mountain Magic’ (Resistance: blight. A tasty cordon type requiring staking and sideshoot removal).