Handbook for Irrigation of Wine Grapes in South Africa

A

B

FIGURE 4.40. Folded lateral ends can be held in place using (A) folded retainers or (B) narrow rings made from polyethylene pipe off-cuts to allow easier flushing.

Clogged drippers are sometimes opened by pinching them with a pair of pliers. If the pinching is repeated, it may deform the drippers causing the flow rate to deviate from the original design (Fig. 4.41). It was previously shown that the flow rate of 4  /h drippers varied between 6 and 21  /h after they had been repeatedly opened by pinching (Myburgh, 1989a). Since this level of variation within an irrigation system is unacceptable, mechanical opening of clogged drippers is unacceptable. Growers are referred to the NETAFIM SA maintenance guide for chemical cleaning of clogged irrigation systems

FIGURE 4.41. The dripper on the right has been deformed by repeated pinching using a pair of pliers.

4.5 CONCLUSIVE REMARKS The choice of an irrigation system depends on the preference of the grape grower. However, given the limited irrigation water resources, periodic droughts, as well as indications of a possible shift towards a drier and warmer climate, higher irrigation system efficiency is becoming more important. Drip irrigation has the

100 CHAPTER 4 – IRRIGATION SYSTEMS