Tolerance to Early Spring Flooding

Ratings are given in days for several species.  This is taken from work in Canada (McKenzie, R. E., Vol. 31, 1951, Sci. Agric. pp. 358-367).  Based on observations, estimates of flooding tolerance of mature plants have been made for other species.  To distinguish between these and the research data these estimates are shown as follows: 

Exc.  =   (excellent) - more than 49 days
Good =  14 to 49 days
Poor  =  less than 14 days

Very little information is available on tolerance to summer flooding.  It is known that plants are far less tolerant to flooding with warm water and even less to still, warm water.  In irrigation systems water should be held on in summer months only long enough to reach the root zone, then drained off.  This should seldom require flooding for more than 24 hours.