Winter overwintering

Meng FJ, Que YM, Han YZ, Li HX, Wang ZC (1989) Isolation of zearalenone from shoot apices of overwintering winter wheat. Sci China 32 1009-1105 (Chinese, Engl, summ.)... 

Winter digging can expose overwintering pests for predation by birds and ground beetles. However, don t go too far when tidying up the garden spare a thought for the beetles, centipedes, and toads that play a vital role in pest control. They need safe, undisturbed locations to thrive. 

Perennials that do not normally survive a cold winter are usually classified, with annuals, as bedding plants, as they too need to be replanted annually. Plants such as pelargoniums or felicia can be overwintered in a frost-free greenhouse or a cool basement, cutting them back and then repotting at the start of spring. 

Cabbage family Dig in winter vetch in the spring, or add compost Sow and plant summer brassicas plant overwintering brassicas with lettuce and other intercrops (see p.259) between. If you don t want so many brassicas, grow sweet corn. Apply compost to the overwintering plants in late summer spread leaf mold over the rest of the plot... 

Pull away old mulches over winter this will clear away some fungal spores and expose overwintering pests to hungry birds. 

Small, yellow-white, wingless, waxy pests with dark spots on the abdomen, found among lettuce roots during summer. Overwinters mainly on Lombardy poplar, moving in June to lettuce and sow-thistle. Root colonies can persist into winter, and may survive in the soil until the next season. See a/so Aphids. 

Groundwater-fed streams in alpine areas have been found to be more productive than other Alpine streams [68, 69], and are expected to be important refugia for overwintering aquatic fauna (Ward et al. 1999). Irons et al. [70] suggested that in order to survive the harsh northern winters, benthic macroinvertebrates move actively into unfrozen flowing waters. Conversely, organisms may actively move... 

In winter older wood is examined mainly to see if there are any overwintering stages of the San Jose scale or red spider mite. 

PRIMARY INFECTIONS. The mildew fungus overwinters as mycelium in the buds. If there is very severe frost in winter, some of the infected buds may die off, as the bud scales are not completely closed. In the closed buds the mycelium produces conidia, which infect the young leaves, blossoms and fruit when the buds open. Infection may occur at the greenbud or redbud stage if weather conditions are favourable. The first symptoms of primary infections can then be seen on the leaves and petals at flowering. Apart from the climatic conditions, for mildew infection to develop the tree must also have susceptible tissue (very young leaves) available. The leaves acquire age resistance to mildew at an even earlier stage than they do to scab. 

The deutogynes (winter females) overwinter under bud scales, in cracks in the bark near bud scales, or under moss and algae on the bark. As soon as the buds open, the overwintering mites migrate to the rosette... 

Winter spraying calcium sulphide (200-250 kg/ha) is used for this. Spraying must be carried out during complete winter dormancy (i.e. before the first green leaf appears). At this high concentration the calcium sulphide solution destroys the scale insects. It also controls spider mites and other overwintering stages. 

DEVELOPMENT OF THE SUMMER FRUIT TORTRIX. The Summer fruit tortrix moths overwinter as young larvae in a cocoon on the tree, usually under the remains of dead leaves. Before flowering the first caterpillars move from their winter hiding-places to the flower huds or rosette leaves and weh several leaves together in order to feed and grow there. They may also feed on the young fruit. The places where caterpillars have fed can later he seen on the fruit as scars of varying depth. 

These beetles overwinter as larvae in the soil. Around apple blossom time the beetles emerge from their winter hiding-places and feed on the leaves and petals. The leaves are eaten from the margin inwards. These beetles can cause considerable damage, especially in nurseries and young orchards. 

Cause Pear leaf blister mites. These microscopic mites live and feed on tissue inside leaves. They overwinter on buds and infest new leaves in spring. Spray plants in late winter with dormant oil or lime-sulfur. 

To control whiteflies, remove nearby buckthorns (Rhamnus spp.), where he pest overwinters. Or spray nearby bnojcthorns in the winter with dormant oil spray. 

If there are only a few galls, prune them off before they open in July. For serious infestations, spray the plant with insecticidal soap as new growth starts the following spring. Or apply a dormant oil spray over the whole plant in late winter to kill overwintering pests see caution above before spraying. 

---