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Materials and Methods: Plant Parts and Their Diseases

Materials Needed for Lesson:

1. Edible examples. Choose common and uncommon examples of each plant part as suggested in Table 1.

Table 1. Typical and atypical examples of plant parts and examples of disease that each plant gets.


Plant Part




Color Photos of Diseased Plant Part


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.)


celery, asparagus


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


lettuce, spinach

onion, garlic

Show the thickened basal leaves of onions and garlic.

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


rose hip (tea)


Point out the small flowers on the florets.

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


apple, orange

cucumber, tomato

Fruits have seeds inside.

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


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.


2. Photographs of the diseased plant parts. Examples are available on-line in the final section of this lesson and can be printed out for this intended use only. Live diseased plants will improve the presentation. Check the Mentor list in this website for a plant pathologist near you who may be able to provide materials.

3. Paper plates, napkins, bite-sized sliced carrots, celery, lettuce, broccoli, cucumbers and popcorn (each in separate containers), salad dressing (Ranch dressing is best received by this age group).

4. Classroom “room parents” or teaching assistants are excellent resources for providing these items.