Examples

Plant Part

Typical

Atypical

Comments

Color Photos of Diseased Plant Part

Roots

carrot, radish

sweet potato

Roots do not turn green if left in the sun.

Fig. 3 Healthy carrots and carrots infected with root- knot nematodes (Meloidogyne spp.)

Stems

celery, asparagus

potato

Potatoes are tubers or underground stems and not roots. Potatoes turn green when left in the sun and have buds in their “eyes.”

Fig. 4. Pink stem rot of celery caused by Sclerotinia sclerotiorum

Leaves

lettuce, spinach

onion, garlic

Show the thickened basal leaves of onions and garlic.

Fig. 5. Soft rot of lettuce caused by Erwinia spp.

Flowers

rose hip (tea)

broccoli

Point out the small flowers on the florets.

Fig. 6. Downy mildew of broccoli caused by Pseudoperonospora spp.

Fruits

apple, orange

cucumber, tomato

Fruits have seeds inside.

Fig. 7. Belly rot of cucumber caused by Rhizoctonia spp.

Seeds¹

pumpkin seeds

popcorn, cereals

Nuts¹ and grains are also seeds

Fig. 8. Common smut of corn caused by Ustilago maydis

¹ Caution! Nuts should NOT be brought into the classroom. Some children have severe allergies to nuts and nut products.