(IPPM) in Vegetables - Vegetableipmasia.org

Resource Manual on IPPM in Vegetable
World Education Philippines, Inc.
search for signs of an insect inside. If there is none, the gall is probably caused by
a disease.
11. Leaf Blisters – These are yellow bumps on the upper surfaces of the leaves with
gray depressions on the lower surfaces.
12. Leaf Curl Diseases – This causes new leaves to be pale or reddish with the
midrib deformed. The leaves pucker and curl as they expand. Certain insects
cause similar symptoms. So on closer inspection, if the insects themselves are the
cause, the insects or other signs of their presence can be seen.
13. Leaf Distortion - Leaves of the infected plant may be distorted from their normal
shape and size. Leaves may be elongated, smaller in size, or thickened. This type
of symptom can be associated with viral, fungal or bacterial infections as well as
insect and mite infestations.
14. Mildews – Mildews are usually one of two types. Downy mildew is usually a
white to purple, fuzzy growth, usually on the undersides of leaves and along
stems. It turns black with age. Powdery mildew is a white to grayish powdery
growth on the upper surfaces of leaves.
15. Mosaic and Ring Spots - Mosaic and ring spots are used to describe an irregular
patchwork of green and yellow areas over the surface of a leaf. In some cases
leaves may also become distorted. Often these symptoms are associated with viral
pathogens. There is not a sharp margin between the affected and healthy areas.
Distinct margins may indicate a nutritional problem or genetic variegation.
16. Necrosis or Death of Plant Parts - These may be some of the most noticeable
symptoms, especially when they affect the entire plant. Examples are wilts or
diebacks. Other examples include shoot or leaf blights, leaf spots, and fruit rots.
17. Overall Stunting and Decline - These symptoms can be caused by several and
very different factors. Systemic viral infections can result in stunting or decline,
but such viral infections are often accompanied by other aboveground symptoms
like shortened internodes. In many cases, overall stunting of a plant may be due to
problems associated with the root system. The roots should be examined for
rotting and possible mycelial growth, reduction in roots especially feeder roots,
and the presence of galls. Root galls can result from fungal and fungal-like agents
(Plasmodiophora brassicae), nematodes (Meloidogyne spp. - root-knot), and
bacteria (Agrobacterium sp.). Abiotic factors such as nutritional deficiencies, soil
compaction and herbicide residues can also result in overall stunting or decline.
18. Overdevelopment of Tissues and Organs - Examples include galls on roots,
stems, or leaves, witches' brooms, and profuse flowering.
19. Powdery Mildew Powdery Mildew can affect leaves, stems, flowers and fruits
with a white to gray surface coating of mycelia which can be rubbed off. Black
specks may later develop in the mycelia. These specks are mature cleistothecia,
the overwintering fungal structures which contain ascospores. Tissue may turn
155