Heat-hit potatoes need extra care in store
This summer’s exceptionally hot and dry conditions could have some significant implications for stored potato crops, so growers are urged to remain vigilant and manage any issues promptly. Hutchinsons head of potato agronomy, James Lee, highlights five key areas to focus on for crops that have been, or are currently, being put into store:
Sprout suppression High temperatures and lack of moisture can reduce the natural dormancy period of potato crops, potentially by up to three or four weeks, therefore sprout suppressants may need applying earlier than normal, says James. “This reduction in dormancy has been well demonstrated this season, where some crops started to develop sprouts pre-harvest, so monitor stored crops carefully.”
He also urges growers to consider the effectiveness of any earlier maleic hydrazide (MH) application when assessing the timing of the first post-harvest sprout suppressant, as conditions for much of July and August were not conducive to optimal performance in some crops. “The quality of the haulm is an important factor in how well, and how much, MH is translocated down to the tuber.”
If in doubt, a laboratory residue test can be useful for confirming whether levels are sufficient for medium to long-term sprout suppression. “It’s worth speaking to your buyer to see if they can arrange a test.”
Bruising risk Lack of water, either due to low rainfall, or where growers ran out of irrigation water towards the end of the season, could have resulted in some crops becoming dehydrated, putting them at increased risk of bruising damage during harvest and store loading, James says. “Low water pressure in a tuber results in a higher risk of bruising should the tuber be subject to a knock or fall.”
Bruising can significantly impact storage quality and longevity, so again, close monitoring is key, particularly where crops were dehydrated at harvest. Moisture loss Preventing unnecessary water loss once crops are in store will help reduce the risk of low tuber water pressure, and the potential increased risk of compression bruising at the end of the storage season, James says. “Moisture loss is greatest in the first few weeks of storage, when the respiration rate is high, and fans are being run constantly to cool and dry the crop and reduce risk of condensation and/or disease. Growers should reduce air flow through the crop as soon as it is dry to prevent further, unnecessary, water loss.”
Watery wound rot Crops should be inspected for any skin damage, such as that caused by the abrasiveness of sandy soil at harvest, as this can provide an entry point for disease, such as watery wound rot. Risk from this disease is highest when soil is wet at harvest and the temperature above 20C. “The initial disease infection causes the flesh to liquify (often referred to as ‘leak’) and during the early stages of infection is often not apparent,” James explains. “Leaking of tuber contents across neighbouring tubers then creates a wet and warm environment that allows secondary bacteria to infect the tubers and stores can fall over very quickly.”
Ventilating the crop well to ensure any infected tubers dry (“mummify”) before their contents can leak is the best way to prevent problems spreading, he adds. Blackleg Finally, James advises growers to remain vigilant for blackleg. Although the hot, dry summer meant levels were generally very low, infection can still occur during storage if the conditions are suitable for bacteria to flourish – I.e. skin damage, temperatures above 2C, high humidity, and condensation.
[Ends, 586 words]
Source: press release issued by Siafu.