BSPP ‘Plant Doctor’ Quiz #18 – September 2022

The correct answer is:

One pathogen

One pathogen, the orange pustules (uredinia) and the black pustules (telia) are both of the same rust pathogen.

The correct answer is:

Two pathogens

Two pathogens on the leaf.  The orangey rust pustules are embedded within the leaf whereas the white powdery mildew is growing over the surface.  Notice that neither pathogen is causing a significant visible host reaction.

The correct answer is:

There is no pathogen involved

There is no pathogen involvement in these symptoms.  This is “bitter pit” symptom in apple caused by a calcium shortage.  Rather like the more familiar blossom end rot in tomato.

The correct answer is:

One pathogen:

This orangey dust is the spores of the rust fungus on an ornamental Oxalis.  (The purple colour of the leaves is not due to the pathogen.) Notice the extreme amounts of spores on the ground as well as in the pustules.

The correct answer is:

There is no pathogen involved

Didn’t mean to trick you, but this is not peach leaf curl (that is not a problem on apple).  It is an insect pest, the rosy apple aphid, that is causing these dramatic symptoms.

The correct answer is:

There is no pathogen involved

Incredible as it may seem, there is no pathogen infection on these leaves.  The necrotic areas are generally described as “stress symptoms” but they can develop even in the absence of any apparent stress on the plant.

The correct answer is:

Three pathogens.

Rust, powdery mildew and Septoria are all infecting this leaf.

The correct answer is:

One pathogen

These are the symptoms of Light leafspot on Oilseed rape. The central leaf spot and the small white dots, as satellites of the spot, are all symptoms of Pyrenopeziza brassicae.

The correct answer is:

One pathogen:

Powdery mildew on laurel can be extremely severe.  The infected area can drop out, giving the impression of insect feeding damage. The black dots among the white powdery growth are the cleistothecia, the sexual stage of the fungus.

The correct answer is:

There is no pathogen involved:

The symptoms on this butternut squash are due to accidental glyphosate drift.