To explain crop failures, aside from easily recognizable factors like pests and diseases, the Karen draw on their animist beliefs. These explanations include phenomenon called Ku Ka Thwee, Bue Koo and Bu Keh, Ku Jute, Bue Plaw Tho and Bue Bloh. The Karen consider these to be more challenging to cope with than the "visible" problems.
Ku Ka Thwee
The Karen believe that if water, honey, sap from a certain poisonous vine, urine or blood from the pangolin (Yu Hor) are spilt onto the soil, the water evaporating from the soil afterwards will kill the plants. Light rain, after the ground has been over exposed to sun, could also have the same effect. These elements will destroy the spirit of the soil and crops resulting in the rice losing moisture and dying. The Karen also believe that the process of burning and tidying the land of excess branches and debris, called Gho Ku, will make the land more susceptible to Ku Ka Thwee.
In order to cure the field from the effects of Ku Ka Thwee, a special species of wild banana (Ya Pla) is planted where Ku Ka Thwee has occurred. This banana variety has high water content and can counteract the Ku Ka Thwee effects. Additionally, three short bamboo poles are placed in the ground, in the areas where farmers practiced Gho Ku, both as an indicator for and as protection against Ku Ka Thwee. The poles are put into the ground together, filled with a salty-sour solution and covered for 3 days. Moisture accumulated in the poles after this period then indicates the presence of Ku Ka Thwee. However, the poles are believed to clear the ground of excess steam and cultivation can continue without a problem.
Bu Koo and Bu Keh
If affected by Bu Koo and Bu Keh, rice seedlings are weakened and could possibly die from premature planting when the ash and soil are too strong for cultivation. The leaves first develop white spots (Bu Keh) and then turn black (Bu Koo). The Bu Koo stage is more serious and more damaging to the seedlings than Bu Keh. This process can be reversed by fermenting the bark of the Dhe Khoo Haw tree in water for 3 days; the smell and the water will cure Bu Koo and Bu Keh.
This phenomenon is caused by late planting. Most of the ash has already been washed away by the rain, hence the soil has less fertility and the seedlings do not grow well. Burning rice husks, letting the smoke spread through the land, and then spreading the resultant ashes onto the field prevents Ku Jute.
Bu Plaw Tho
This is caused by overly wet or dry conditions which are detrimental to young rice seedlings, especially during the flowering period.
Bu Bloh occurs when rice is grown too fast on poor quality soil. The rice will not produce grains and will die. It is difficult to get any seed from plants affected by Bue Bloh. To prevent Bu Bloh, the plants are cut back before flowering to slow down the growth so that when they flower, the plants will produce seed.