All about potatoes.pdf - Vegetableipmasia.org
All about potatoes.pdf - Vegetableipmasia.org
All about potatoes.pdf - Vegetableipmasia.org
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9.<br />
DISEASE ECOLOGY<br />
• The environment supports the development of the pathogen, for instance:<br />
o Suitable temperature and relative humidity for disease development (often high<br />
temperatures and high humidity).<br />
o The presence of pathogen carriers, such as wind, water, farming tools, insects,<br />
etc.<br />
These three factors are related to each other as depicted in the so-called disease<br />
triangle (see Figure 3).<br />
Disease source<br />
Environment<br />
Host plant<br />
Figure 3: The disease triangle<br />
A disease management strategy can be designed by influencing or changing any one<br />
of these factors of the disease triangle, and hence obstructing disease development,<br />
for instance in the following ways:<br />
Influencing the DISEASE SOURCE by:<br />
• Reducing the presence of diseases in the field by carrying out sanitation,<br />
destroying infected plants, selecting disease-free fields, using clean water for<br />
irrigation and using disease-free seed.<br />
• Breaking the disease chain by rotating crops.<br />
• Using composted <strong>org</strong>anic fertilizer, which increases the quantity and role of living<br />
<strong>org</strong>anisms that can combat diseases, and does not introduce disease causal<br />
agents.<br />
Influencing HOST PLANT health by:<br />
• Using healthy seed to produce a homogeneous, healthy crop.<br />
• Providing balanced fertilization and using composted <strong>org</strong>anic fertilizer to promote<br />
plant health.<br />
• Using resistant varieties where possible.<br />
Influencing and changing ENVIRONMENTAL conditions by:<br />
• Planting <strong>potatoes</strong> at the end of the rainy season or at the end of the dry season,<br />
so the weather is drier and less suitable for disease agents to develop (note: this<br />
refers to wet tropical highland conditions).<br />
• Making seedbeds higher in the rainy season so the soil is not too wet or moist.<br />
• Adjusting planting density as to reduce humidity around the foliage during the wet<br />
season.<br />
56<br />
ALL ABOUT POTATOES