Pests & Diseases

FILTER:

Aphids

Aphids

EFFECT

Eat forage.

There are usually two flights per year with the first occurring from late spring/early summer and the second from late summer/early autumn. It is during the nymph stage that feeding damage occurs to plants.
 
Brassica crop plantings from November to March are usually the most vulnerable to Aphid attack.

CONTROL

  • Ultrastrike seed treatment
  • Aphid-tolerant varieties
  • Application of insecticide
  • Recognise flight periods and control infestations early

Argentine Stem Weevil

Argentine Stem Weevil

EFFECT

Larvae appear from October onwards and feed on tillers causing them to yellow and then brown and ultimately die. Poor resulting of pasture is often mistakenly attributed to other factors such as drought. Adult weevils feed all year round on leaves leaving narrow rectangular holes in the leaves usually near the tips. 

CONTROL

  • Use of Ultrastrike brassica or Superstrike Grass seed treatment to protect seedlings
  • Removal of host ryegrass plants
  • Recognise flight periods and control infestations early
  • Application of insecticide
  • Use tolerant species (cocksfoot, tall fescue)
  • Use of grasses with standard, AR1, Endo5, AR37 or MaxP endophytes

Black Beetle

Black Beetle adult

EFFECT

A major pest in the northern North Island, Black Beetle larvae feed on the roots of grasses over summer causing the pasture to become loose and open and the damage appears similar to that of Grass Grub.

CONTROL

  • Use of Superstrike seed treatment to protect seedlings
  • Use of grasses with standard, Endo5, AR37 or maxPendophytes
  • Insecticide application
  • Use of a Summer forage crop (e.g. Pasja II forage brassica)
  • Use of resistant species (e.g. lucerne)

 

Black Field Cricket

Black Field Cricket

EFFECT

Grass plants may be completely consumed down to the crown. Seeds and seedlings are attacked also, so areas with heavy infestations may become totally devoid of vegetation.

CONTROL

  • Application of cricket bait for Black Field Cricket control
  • Insecticide application
  • Use of a summer forage crop (e.g. Pasja II forage brassica)

Black Rot

Black rot

EFFECT

A fungal disease that rots brassica leaves

CONTROL

  • Bury previous crop debris
  • Crop rotation

Clover - Leaf Spot, Blights & Blotches

Clover Blotches

EFFECT

Forage quality may be affected by spotting and defoliation and this may have an effect on pasture yield.

CONTROL

  • Timely grazing and harvesting

Clover Nematodes

Clover Nematode

EFFECT

Invades clover roots and cause damge at the growing tip which allows root disease to occur. Damage may result in dwarfing, discolouration, wilting and plant death.

CONTROL

  • Use of Superstrike Clover seed treatment to protect seedlings
  • Newer cultivars with greater tolerance
  • The Programmed ApproachTM

 

Clover Root Weevil (CRW)

Clover Root Weevil

EFFECT

Invades clover roots and cause damage at the growing tip which allows root diseases to occur. Damage may result in dwarfing, discolouration, wilting and plant death.

CONTROL

  • Use of clovers with a higher tolerance to CRW (e.g. Kopu II large leaf white clover)
  • Nitrogen fertiliser to reduce effects of reduced nitrogen fixation
  • Cultivation/ The Programmed ApproachTM

Clover Viruses

Clover Virus

EFFECT

Symptoms are not always obvious but may be more noticeable in spring and autumn growth. Symptoms may vary from leaf mottling, distortion, crinkling and size reduction through to plant stunting. 

CONTROL

  • Use of tolerant or resistant cultivars where available
  • Sowing cultivars well adapted to a region to reduce plant stress and virus susceptability
  • Allowing new pastures to establish well before stocking or mowing
  • Control of aphid infestations

Clubroot

Clubroot

EFFECT

An infection that can occur in all brassica species and is a soil borne fungus that can remain dormant in the soil for many years and can re-emerge only when a brassica crop is planted. This makes it extremely difficult to eradicate or prevent. 

CONTROL

  • Crop rotation
  • Use kale

Damping Off

Damping off diseases

EFFECT

Symptoms characterized by either the failure of seedlings to emerge or the toppling over and subsequent death of newly emerged seedlings. Plants that are affected post-emergence usually appear shriveled and discoloured at the shoot base. Damping off pathogens cause infection over a wide soil moisture and temperature range. 

CONTROL

  • Use of Superstrike grass or brassica seed treatment to protect seedlings
  • Chemical control

Diamondback Moth

Diamond Back Moth

EFFECT

Lay eggs in brassica plants and can cause damage to leaf and seeds.

CONTROL

  • Removal of old brassica plants which may act as carry-over hosts
  • Application of insecticide

Dry Rot

Dry Rot

EFFECT

Dry rot appears in a crop as a leaf spotting, small green-grey lesions about 3-5 mm in diameter appear on young leaves from around the 3-4 leaf stage onwards (in a swede crop this is often
between Christmas and New Year). 

CONTROL

  • Use kale
  • Crop rotation and minimise crop residual in second year crops

Grass - Leaf Spot, Blights & Blotches

Grass blotches

EFFECT

Localised damage to ryegrass pastures throughout new Zealand. Disease causes loss of green leaf, reducing forage value and dry matter production.

CONTROL

  • If disease is noted as increasing, graze or cut to stop infection build-up
  • Fungicide (Strobilurin) application

Grass Grub

Grass grub

EFFECT

Plants wilt and may eventually die due to the roots being eaten away. Yellow patches of stunted growth appear in the pasture and plants may be readily pulled from the ground due to loss of roots. Period of maximum feeding by grubs is in autumn and early winter.

CONTROL

  • Heavy grazing (March-June) to reduce Grass Grubs' feed supply
  • Through cultivation in spring
  • Granular intesicide sown in the root zone
  • Heavy stocking or rolling to squash larvae
  • Use of Superstrike Grass seed treatment to protect seedlings
 

Greasy Cutworm

Greasy Cutworm larvae

EFFECT

Eat forage leaves

CONTROL

  • Good seed bed cultivation and compaction
  • Application of insecticide

Leaf Miner

Leafminer

EFFECT

Eat forage causing damage to leaves

CONTROL

  • Removal of alternative hosts (e.g. fathen, sowthistle etc.) to prevent build-up of numbers

Leaf Spot

leaf spot turnip

EFFECT

Discoloured spots on brassica leaves

CONTROL

  • Insecticide 

Pasture Mealy Bug

mealy bug damage

EFFECT

Most damage is a direct result of feeding so that only high populations are important. infestation can be recognized from the surrounding white wax substance found in the crown of the plant.

CONTROL

  • Use  of grasses with standard, AR1, Endo5, AR37 or MaxPendophytes

Pepper Spot

Pepper spot

EFFECT

Leaves and petioles develop numerous, small discrete spots. Leaves turn brown, appear scorched and drop. A common disease of clover in wet areas from mid-summer.

CONTROL

  • Timely grazing and harvesting
  • Chemical control

Porina

Porina

EFFECT

Caterpillars build vertical tunnels into the soil from which they emerge at night to feed on pasture plants. Bare patches appear in the sward and the incidence of flat weeds may increase along with fine cast of dirt which may appear on the surface. 

CONTROL

  • Use of grasses with AR37 endophytes#
  • Regular pasture monitoring
  • Mob stocking of pastures to prevent rank pasture and build-up of debris
  • Insecticide application
  • Heavy stocking or rolling to squash larvae
Note: in pastures with AR37 ryegrass, Porina can be present and feed on the pasture mix components.

Ring Spot

Ringspot

EFFECT

Circular lesions on brassica leaves

CONTROL

  • Crop rotation

Rust

Rust

EFFECT

Rust infected plants are less vigorous and smaller than those without the disease so there are reduced yields as well as a reduction in palatability and nutritional quality.

CONTROL

  • Timely grazing and harvesting
  • Chemical control

Slugs

Grey field slug

EFFECT

Feeding takes place mainly at night, and will be shown as holes in the leaves, stems or roots. Slime is a good indication of slugs or snails.

CONTROL

  • Monitor slug numbers
  • Slug Bait application

Springtail

Springtail

EFFECT

Damage to brassicas may occur as soon as the seed shell is shed and the cotyledons emerge, and as a result the stems supporting the cotyledons are often damaged or destroyed before they emerge above the soil. With mouthparts adapted for chewing, Springtail chew small holes or pits in leaf surfaces.

CONTROL

•Ultrastrike Brassica or Superstrike Brassica seed treatments
•Contact insecticide
•Both seed treatment and a contact insecticide is recommended in no-tillage situations
 

Wheat Bug (Nysius)

Wheat Bug Nysius

EFFECT

When feeding on brassica seedlings the developing plants become weak at ground level and often fall over. Nysius damage is often identified by a “ringbarking” effect at the base of the plant. Nysius are most active in dryland regions with increased plant damage occurring under hot, dry conditions over the summer months. Nysius prefer an open ground cover.

CONTROL

  • Ultrastrike Brassica seed treatment to protect seedlings
  • Control of weeds around crop borders will help reduce localised numbers
  • Application of insecticide

White Butterfly

White Butterfly

EFFECT

Eat forage leaves

CONTROL

  • Natural predators (e.g. hoverfly, harvestman and parasitic wasps)
  • Removal of old brassica crop, debris and weeds to prevent overwintering and localised build-up

White Fringed Weevil

White fringed weevil

EFFECT

Eat forage leaves

CONTROL

  • Thorough cultivation should be carried out through late spring and summer prior to sowing in infested areas; clean fallow reduces numbers
  • Apply insecticide sown with seed

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