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.
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.
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.
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.
A fungal disease that rots brassica leaves
Forage quality may be affected by spotting and defoliation and this may have an effect on pasture yield.
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.
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.
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.
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.
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.
Lay eggs in brassica plants and can cause damage to leaf and seeds.
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).
Localised damage to ryegrass pastures throughout new Zealand. Disease causes loss of green leaf, reducing forage value and dry matter production.
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.
Eat forage leaves
Eat forage causing damage to leaves
Discoloured spots on brassica leaves
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.
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.
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.
Circular lesions on brassica leaves
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.
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.
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.
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.
Eat forage leaves
Eat forage leaves