Broccoli Pests and Diseases

Keep your eyes peeled for broccoli pests and diseases as they can quickly rob you of your future veggie profits.

With broccoli pests, do as the tax department does... tax (squash) everything. If it moves, tax it more (chase it and squash it harder)! 


Can't help you with tax, but below is a list of all the broccoli pests and diseases you're likely to come across. For general garden problems with pests, animals, birds and diseases, see Organic garden pest control.

You might get no broccoli pests and will probably grow marvelous disease-free plants, but just in case, here are some possible challenges:

Caterpillars, which include cabbage worms, cabbage loopers and army worms:

broccoli pests - caterpillars, cabbage worms, cabbage loopers, eggs

Watch for these as they tend to like to invite themselves to dinner on your broccoli leaves. Your plants are goners if caterpillars eat out the growing tips.

Here's a handy hint or two for caterpillars: Before broccoli and cabbages form heads, sprinkle the leaves with cayenne pepper powder. This should deter the little blighters.

Also of course, as well as picking caterpillars off, an organic solution is Bt (Bacillus thuringiensis). By dusting or spraying this every 7-10 days, it controls caterpillars, especially cabbage worms, the nastiest of the broccoli pests. More solutions at Organic garden pest control.

There are two types of cabbage white butterflies — large and small. Both types overwinter as pupae and in springtime they emerge as white butterflies, mate and lay their eggs which hatch into leaf chewing caterpillars about 2 weeds later.

The large cabbage white butterfly caterpillar lays a cluster of yellow eggs usually on the underside of a leaf, and the more common and destructivesmall white butterfly lays single white eggs.

Cabbage looper moths mainly fly at dusk and are brown with a light silver spot on each main wing. They lay many single dome-shaped eggs on the underside of leaves. The eggs hatch around 3 days and the caterpillars move by arching their middle or looping along.

Army worms are pale green when young, darkening and developing stripes and patterns after about 10 days. The moths are mottled brown and lay fuzzy pale eggs in a mass. These hatch out in 2-4 days and the worm eat holes in the leaves or burrow into the growing tips of plants. 

Broccoli pests - armyworms, armyworm moth

Cabbage root maggots:
cabbage root maggots and fly
Sound awful don't they? Broccoli think so too, as they collapse in their death throes. These broccoli pests are fly larvae the size of a grain of rice which feed on the roots.

Any sign of them, particularly if you've had previous trouble, make sure you firm the soil well around each seedling. This stops the larvae hatching.

Also before you mulch, make sure you put paper layers or cloth close to the stem of each plant to prevent adult flies from laying eggs in the soil.

Damp, humid weather seems to encourage aphids, especially in the spring. It only takes a few warm days and suddenly the crowds have arrived. Tackle aphids immediately because they can suck the sap and stop the new growth. Garlic fire spray is a winner at  Organic garden pest control.  

broccoli pests - aphids

clubroot in broccoliClubroot:
This broccoli problem is caused by a fungus in the soil. Growing your own plants from seed helps, as most clubroot fungus is introduced from brought in plants with infected roots.

Clubroot symptoms are wilted, discoloured leaves, and when you pull out a plant, its roots will be a tortured, thick mass of... well, clubroots. It's no wonder the plant looks sick, as the roots simply are unable to do what roots normally do.

There is no effective organic treatment for clubroot fungus once it gets into your garden, so there are not many options unfortunately. Most importantly avoid planting broccoli or any brassicas in the same patch for another 4 years at least, and from then on, make sure you rotate brassicas leaving three years inbetween crops. If feasible, replace your soil.

If your soil is acidic, add lime at least 2 months before planting, because clubroot prefers acid soil conditions.

downy mildew on seedling leavespowdery mildew on leafOne of the irritating broccoli pests and diseases is mildew.

It takes a lot to kill a plant, but it will if it gets out of hand. Springtime with milder, but damp weather encourages mildew.

There are two types of mildew:
Downy mildew: is the most common and forms greyish, powdery patches, mostly on the leaves and new shoots at first. Downy mildew will invade the plant's insides eventually, and lethally.

Powdery mildew:
This is more a surface mildew, and appears in scattered patches.

Botrytis, or Grey mould:
botrytis or grey mould on leafThis is another one of the common broccoli pests and diseases which is caused by damp conditions. Botrytis often attacks very new seedlings, especially if the soil is highly fertilised. It starts off often on the stems as brown spots or patches which change into a greyish furry mould. Young plants especially keel over and die pretty quickly once afflicted.

Conditions that encourage mildew and moulds are over-watering, over-crowding and over-feeding. Putting seedlings that are in pots or trays outside in a breeze or good air flow will help. 

bacterial soft rot on broccoliBacterial soft rot:
Wet and warm conditions can bring on this rotten problem. It's usually in the middle of a broccoli head and starts as a small darker, soft patch. Within a week the whole head can be infected and looks, as the name says, softly rotten, sunken and brown.

If you are getting long spells of warm temperatures along with rain, then keep an eye out and remove any infected plants before it spread to your whole crop. If you need to water, do so in the morning or when the heads can dry quickly.

Some broccoli varieties are more resistant than others, and flat-headed types are naturally more susceptible to broccoli soft rot where water can sit. Dome shaped types and sprouting varieties are less likely to succumb as the water can run off easily.

For solutions to all the above broccoli pests and diseases, see Organic garden pest control.