Occurrence And Control Techniques Of Iron Deficiency Chlorosis Of Peach Trees In Central Hebei

The central Hebei as an important peach production area in China,the problem of iron deficiency chlorosis of peach trees has gradually attracted the attention of fruit farmers with the continuous development of peach industry.At present,there have been a lot of reports on the diagnosis and correction of iron deficiency chlorosis of fruit trees.However,the occurrence regularity of iron deficiency chlorosis of peach trees is still unclear,and there is no efficient and simple operation method for the actual production of fruit farmers.Thus,this paper took the peach trees in Shenzhou and Xinji city as the research objects,and tracked the orchard management information and measured leaf chlorophyll(SPAD)values in 2017-2018.The two-year peach soil and plant nutrient content were determined.On the base of these works,the occurrence regularity of iron deficiency chlorosis of peach trees and its influencing factors were researched.At the same time,field trial and verification experiment were carried out,and the prevention and treatment methods for the iron deficiency chlorosis of peach trees were discussed,this work provides a theoretical basis for the diagnosis and treatment of peach leaf chlorosis disease and improving fruit quality.The main results are as follows:(1)The iron deficiency chlorosis of peach trees have certain occurrence rules in terms of tree orientation,branch position,canopy level,variety and period.The peach tree with iron deficiency chlorosis in the same disease happened period had the lowest SPAD value of 32.6 in the southeast direction,which was more serious than other directions of iron deficiency chlorosis,followed by southwest,northeast and northwest direction,the value was 34.7,37.3 and 41.6,respectively.About the shoot position,the top leaf SPAD value was the least 22.8,which was more severe than other parts of the iron deficiency chlorosis.At the canopy level,the high-level SPAD value was 23.7,which was far lower than the middle and lower layers,and the chlorosis phenomenon was serious.In respect of peach varieties,the late-maturing peach easily occurred chlorosis phenomenon;the iron deficiency chlorosis orchards of late-maturing variety in 2017 and 2018 accounted for 47% and 37% of the total orchards,respectively.And the average SPAD value of late-maturing variety peach of chlorosis in two years was 22.7 and 30.8,respectively.From the inter-annual variation of the SPAD value of iron deficiency chlorosis peach trees,starting in April and the range would rapidly expanded in July.So,it was necessary to focus on prevention and treatment of iron deficiency chlorosis leaf disease in July.(2)Soil and plant nutrient status and fertilization amount have significant effects on iron deficiency chlorosis of peach trees.By analyzing the nutrient content of peach orchard soil and plant,it was found that the content of nitrogen,phosphorus,potassium and trace elements copper and zinc were positively correlated with the ratio of peach chlorosis leaves.There was a significant negative correlation between the ratio of effective iron and chlorosis leaves;and the same trend varies from year to year.There was a significant positive correlation between the input of NPK nutrient and the symptoms of iron deficiency and chlorosis in peach trees.Therefore,the increase in nutrient content and input of NPK will greatly increase the symptoms of iron deficiency chlorosis leaves,while the application of iron fertilizer will inhibit the occurrence of iron deficiency chlorosis leaf disease.(3)The application of iron fertilizer can effectively prevent iron deficiency chlorosis of peach trees.From the greening situation of the control test leaves,EDDHA iron,fulvic acid iron,vivianite,vivianite + fulvic acid iron and vivianite + EDDHA iron treatment can increase the SPAD value with no iron fertilizer,and increased 27,29,31,29,25,respectively.From the aspect of improving fruit quality,EDDHA iron and iron fulvic acid treatment can significantly improve the fruit solid-acid ratio,in which EDDHA iron was higher than iron fulvic acid,improving 3.8% in the prevention test and 7.1% in the correction test.But the combination of soil application and spraying applied iron fulvic acid treatment was higher 2.8% than EDDHA iron treatment and the treatment of iron fulvic acid could effectively improve the horizontal and vertical diameter of the fruit and satisfy the need of fruit farmers.The demand is also the cheapest,and the economic input is also the cheapest.Therefore,the effect of iron fulvate on the prevention of iron deficiency chlorosis of peach trees was the best.In short,the iron deficiency chlorosis of peach trees have regular follow-up and occurrence of nutrient content,so it needs to be observed in time,the application of iron fertilizer such as iron fulvic acid in the germination stage and the early stage of the disease can prevent and cure the iron deficiency chlorosis disease of the peach tree,thereby realizing the leaf greening,improving the single fruit weight and improving the fruit quality to achieve the high quality and yield of peach.