No matter what type of fodder brassica you’re growing this year, there’s one rule of thumb that applies in every situation: the higher your final yield in kilograms of dry matter per hectare (kg DM/ha), the cheaper the cost of feed.
Few things can influence that equation faster or more negatively than insect pests, particularly in the early stages of crop establishment. Brassica seedlings and young plants are very vulnerable to pest infestation, and once they have been affected, it’s difficult to reverse the impact on your final DM yield.
Springtails, greasy cutworm, aphids, Argentine stem weevil, diamond back moth, white butterfly caterpillars, leaf miner and Nysius (wheat bug) can all cause considerable economic damage in fodder brassicas.
If you catch them early, however, most pests can be effectively controlled with appropriate insecticides. The best way to stay one step ahead of any potential issues is to start looking for pests from the first signs of seedling emergence.
Check the crop every one or two days for the first few weeks, then at least once a week after that. The most costly insect pests are usually small and good at concealing themselves, so you’ll get the best indication of what’s around by walking through the crop and inspecting the underside of leaves and the plant crowns for damage and pests.
Springtails will begin to attack as soon as brassica seedlings start to emerge. These tiny pests can eat right through the stem, destroy the growing point or totally defoliate seedlings.
Greasy cutworm will completely eat newly-emerged seedlings and leave just the stalks, while older seedlings can have the stems cut near ground level, leaves severed or be completely defoliated.
Aphids stunt brassica seedlings and reduce their vigour. They carry diseases that severely impact brassica growth and bulb development. The larvae of leaf miner live and feed within the leaf and leaf veins, creating whitish tunnels in the leaf and causing premature leaf death and yield losses.
Nysius adults and juveniles feed at the base of the plant stem, causing ring barking and cankerous growths. These can kill seedlings or lead to brittle stems that break during windy conditions. Caterpillars of both the diamond back moth and white butterfly feed on the plant leaves, creating holes between leaf veins and, in severe cases, skeletonising the leaves.
Attack® is a broad-spectrum insecticide which provides excellent control of springtails, Argentine stem weevil, aphids, leaf miner, Nysius and diamond back moth and white butterfly caterpillars.
For greasy cutworm control in fodder brassicas, use Kaiso® 50WG or Sheriff® 100 which is now registered for use in fodder brassicas. Sheriff can also be used to control diamond back moth and white butterfly caterpillars.
Your local Fonterra Farm Source TSR can provide more advice about safeguarding your brassica yields from insect pests – give them a call today or ask in-store.
®Kaiso and Sheriff are registered trademarks of Nufarm Limited. Attack is a registered trademark of Nufarm Technologies USA Pty Ltd.
Article supplied by Nufarm