Sunburn is a physiological disease caused by the continuous exposure of the peel to the hot sun during the growth or ripening process of citrus fruits.
The danger seasons each year for citrus sunburn in the South East of China is from July to September.
It is one of the leading causes of abnormality in citrus fruit and causes dropping, which not only affects fruit quality, but also seriously impacts the overall yield of the orchard.
To provide a solution and guidance about this problem that troubles citrus growers, the RLF Technical Team conducted a demonstration of the RLF crop nutrition program at a base in Jianyang District, Nanping City, Fujian Province.
The experimental results showed that the RLF crop nutrition program could effectively reduce the incidence of sunburn, improve the brightness of the fruit skins, and improve the quality of citrus.
The RLF Crop Nutrition Program for Preventing Sunburn
|Location||Jianyang District, Nanping City, Fujian Province|
|Trial details||Control crop used another fertiliser, but the same water management was applied as the RLF program. RLF crop was a prescribed foliar program on specified days.|
|Usage Date||Products Applied|
|15 May||Fruits and Veggies Plus (1L) + Caltro Foliar (1L) + 1,000L water|
Return Visit to Evaluate the Trial Program
On 10th August 2020 the orchard was visited by the Technical Team and this is what they found.
- According to on-site counting, the average hanging fruit was 70 per tree.
- The average number of sunburnt fruits was about 8, accounting for about 11.4%.
- At the time of evaluation, the region’s intense light, and high-temperature weather will continue for some time, so it is likely that further burning could occur in coming days.
- The heat duration in the demonstration area was longer than in the control area.
- In the same fattening water management conditions, the rate of sunburn was significantly reduced with the foliar scheme of Fruits and Veggies Plus + Caltro Foliar.
- According to on-site counting, the average number of hanging fruit was 73 per tree, and there were some individual fruits with sunburn phenomenon, but the degree of damage was slight.
- The average number of sunburn fruits was 3 per tree, accounting for 4.1%.
The demonstration of the RLF crop nutrition program was well received by the growing base’s boss. He expressed his keen approbation and said “that the prevention effect is very good and compared to last year’s burn rate is much less”. He went on to say, “we will continue to use the RLF products on all our crop”.
Strengthening the management of fertiliser and water use, and improving the resistance of fruits to environmental effects are vital. Once growers enter the high-temperature drought period, they should irrigate in a timely manner to satisfy the demand of moisture to the citrus trees. RLF Fruit and Veggies Plus, together with Caltro Foliar should be added into the spraying routine, in accordance with instructions, to promote the photosynthesis of the plant, increase the chlorophyll content of the leaves, and promote the absorption of nitrogen, phosphorus and potassium.
Caltro Foliar can increase the strength and toughness of the peel and assist with the transport of water, improve strength of leaf and fruit, thereby increasing the resistance and reduction of sunburn, crack and fruit fall.