While brassica growers have to contend with the buyer’s interpretation of quality in a volatile market, the weather has made the growing season difficult, with long dry stretches resulting in stressed plants.
Tom Decamp, area manager and field vegetable specialist for Yara, has put together a series of recommendations for farmers struggling with this. He notes the long, cold spring, which led to a prolonged dry spell which has left crops struggling.
“We have had a challenging spring, so plantings were generally later,” Mr Decamp said. “The soil temperatures didn’t get up to 5 or 6 degrees until very late into the spring so plantings went in cold and they’ve struggled. Then we had a prolonged dry spell. That means the plants are small, they’re stressed, and they need a bit of a pick-up.”
While NPK dressings at planting would normally be enough to get crops off to a good start, where there was not enough moisture in the soil, crops will have struggled with nitrogen uptake. This leads to top dressings.
“What the crops are really wanting is some sort of tonic,” he explained. “They need water as much as anything. Years ago, growers would have applied a straight ammonium nitrate type fertiliser to get the crop going. But we’ve had lots of problems with scorch, particularly in the dry conditions with straight ammonium nitrate.”
Scorching can be caused by ammonium nitrate settling in the leaf fold on certain crops. Instead, Mr Decamp recommends calcium nitrate products, such as Tropicote. “It provides instant nitrate nitrogen and readily available calcium and there’s very little risk of scorch. Apply it little and often and you’ll get that instant pick up, even in dry conditions.”
He added that it mixes well with other products, meaning that multiple applications can be done in one pass. “It mixes well with fungicide and pesticide,” Mr Decamp said. “You can also mix it with the YaraVita BRASSITREL PRO liquid which is a micronutrient product.”
Boron and disease resistance
Mr Decamp notes that boron is just as important as calcium and nitrogen for healthy brassicas, and can help avoid issues such as heart rot and internal stem rot.
“Research has found that there’s a big synergy between calcium and boron,” he said. “Calcium, boron, and nitrogen nitrate worked particularly well together so we’d recommend applying a product like Nitrabor to a brassica crop for best results.”
The right mix of calcium nitrate and boron may also help to stop club root, although research is ongoing. “Club root is present wherever you’re growing brassicas in the UK, particularly in Lincolnshire, where most fields will have areas of club root. Club root loves moist soils. The spores swim to the root hair and that’s how it affects the crop. To prevent it, the first step is getting the soil pH right, so you can lime it.
“For some reason, the spores don’t like swimming through a soil solution enriched with those two nutrients,” Mr Decamp added. “So we are seeing the reduction and suppression of club root through using products like Nitrabor.”
Foliar applications
He concluded by noting that foliar applications of NPK may help give crops an extra boost after extended dry spells. “They act like tonics basically. You put a bit of water onto the crop and you are giving them a bit of a boost- and you do see instant reactions. That will keep them going until we get the rain. As well as getting them to pick up, it keeps them in good order externally and internally. So you’ll have a good looking viable crop when you reach harvest.”
Mr Decamp added that Yara’s BRASSITREL PRO would be a good choice for foliar applications, applied at 3-4 litres per hectare; little and often at 10 to 14-day intervals. It can also be tank mixed with fungicides and other products.
For growers, he said that having a good nutrient management plan is a sound investment. “Buyers will be put off by things like scorch, internal browning, size, or other defects,” said Mr Decamp. “For a crop that is marketable without any blemishes or penalties for internal quality, a good nutrient management programme is well worth the investment.”
