为了进一步探明玉米丝黑穗病对玉米产量造成的损失程度，对5个感玉米丝黑穗病品种进行发病情况观察及对产量损失影响程度的测定。经2个试验点调查发现，每个品种感病后部分病株都有分化穗的能力，一般分化穗株占病株数0.51%~14.64%，并且分化穗全部在病穗上位叶。其中病株分化穗表现为可授粉穗能够正常结实，并有商品价值；可授粉结实但灌浆不足，无商品价值；可授粉仅有粒型但未能灌浆；分化穗未能授粉等类型。结果表明少量病株分化穗株具有一定的结实能力，病株分化穗株结实产量比病株率减少损失0.13%~1.27%，因此玉米丝黑穗病产量损失率小于发病率。

The effect of loss rate of the corn yield and disease situation by differential ear of head smut plant is investigated in five corn varieties, in order to confirm the yield losses of maize head smut on corn. The results of two sites showed that, part of diseased plants have differential ear that account for 0.51%-14.64% percent of the disease plants in the top leaves. There were four forms of differential ear, normal pollination and seed, normal pollination but undergrain-filling, normal pollination but cannot grain-filling, fail to pollinate. So the loss of yield could be reduced 0.13%-1.27% percent due to the yield of differential ear, so the loss rate of the corn yield was lower than head smut’s incidence.