Plant Protection 3 : Selected Ornamentals, Fruit and Vegetables

CARNATION
Postharvest
Harvest: When flowers of standard cultivars are almost fully open, or at 'paint brush' stage with half-open
flowers. Harvest spray cultivars with 2 fully open flowers on the stem. After harvest grade flowers
according to bud size and stem length and bunch according to prescribed standards. Tighter buds may
be opened later with either preservative or bud opening solutions depending on the stage of development.
As flowers are sensitive to ethylene, growers may treat flowers with anti-ethylene chemicals immediately
after harvest to extend or double vase life. Avoid sunlight, draughts, keep flowers dry (Nowak and
Rudnicki 1990). Avoid damaging flowers and maintain strict hygiene in the packing shed. See
Postharvest N 62. A Melbourne-based company (Florigene ) has developed an Agrobacterium-mediated
gene transfer system for inserting anti-ethylene genes into any carnation cultivar. This will extend vase
life and reduce the need for anti-ethylene treatments to extend vase life and preservatives (Moody 1994).
Storage/Transport: Flowers can be kept for short periods in a cool room in preservative and wrapped
in plastic (Jones and Moody 1993). Overseas fully open flowers may be stored at 3-4 o C in preservative
solution for up to 2 weeks, at paint brush stage store dry in moisture-retentive boxes at about 0 o C for 3-4
weeks (Nowak and Rudnicki 1990). Buds may also be stored.
Vase life: Recut stems and place in warm water with biocide for a few hours. Allow flowers to rehydrate
for a few hours before putting in sugar solutions, eg floral preservative. Remove dying flowers and
damaged buds regularly, remove foliage below the water line. Replace vase water regularly (Jones and
Moody 1993). Salt concentrations of 200 ppm decreases vase life of carnations and chrysanthemums.
Potted plants: Potted plants are ready for sale when flowers begin to open; plants require bright indirect
light, a temperature of 18-20 o C and moderate watering (Larson 1992).
Fig. 25. Tomato big bud phytoplasma
(greening) on Dianthus sp.
Fig. 27. Left : Aphids, commonly green peach aphid (Myzus persicae).
Centre : Thrips (various species) feed on leaves, buds, flowers.
Right : Twospotted mite (Tetranychus urticae).
Fig. 28. Corn earworm
(Helicoverpa armigera)
feeds in buds and flowers.
NSW Dept. of Agric.
Fig. 26. Fungal leaf spots
(several species of fungi).
Fig. 29. Twisting of leaves caused by
low temperatures. NSW Dept. of Agric.
A 20
ANNUALS AND HERBACEOUS PERENNIALS