Gadenin日本語Get the appWhen problems tend to appear
Through winter and early spring a well-sited godetia has few problems. The risk rises sharply just before and during flowering, when the plants are at their largest, the canopy is dense, the weather is warming and humid spells are common. That is the stage to walk the bed every few days and look at the base of the stems and the undersides of the leaves.
Almost every serious problem traces back to the same conditions: soil that stays wet, plants packed too closely, too little sun, or soft growth from too much nitrogen. Fixing the site is more effective than any spray.
| Problem | What you see | What to do |
|---|---|---|
| Stem rot | Stems darken and soften at soil level, the plant wilts and collapses | Remove affected plants with their soil; improve drainage and spacing |
| Powdery mildew | White powdery patches on leaves and stems, leaves curl and yellow | Remove the worst leaves, open up the planting, water at the base |
| Aphids | Clusters on shoot tips and buds, sticky leaves, distorted growth | Rub or hose them off; encourage predators; soap spray if heavy |
| Thrips | Silvery streaks and flecks on petals, buds that open deformed | Pick off damaged flowers; keep plants watered; blue sticky traps |
Stem rot at flowering time
Stem rot is the problem most likely to take out whole plants. The base of the stem turns dark and water-soaked, the tissue softens, and the plant suddenly wilts even though the soil is moist. It is caused by soil-borne fungi that thrive when the crown sits in wet ground, particularly in warm humid weather as flowering begins.
There is no cure for an infected plant. Pull it out, take the soil immediately around the roots with it, and put it in the trash rather than the compost. Then look at why it happened: heavy soil, a low spot that holds water, overwatering or overcrowding. Raised beds, the right spacing and letting the surface dry between waterings prevent most cases, and it is wise not to grow godetia in the same spot the following year.
Powdery mildew
Powdery mildew shows as a white or pale dusting on the leaves and stems, usually starting on the lower foliage. Unlike many diseases it spreads best when the air is humid but the leaves are dry, so it often appears in still, crowded plantings during the warm days of late spring, and on plants that are dry at the root.
Pick off badly affected leaves, thin the planting if it has closed up, and water at the base in the morning so the plants are neither stressed by drought nor sitting in humid, stagnant air. On plants that are nearly finished flowering it is usually not worth treating; on young plants a potassium bicarbonate or sulfur product labeled for ornamentals can slow it down if applied early.
Mildew on the lower leaves late in the season is normal as the plant winds down. It matters most when it appears early and reaches the flowering stems.
Aphids and thrips
Aphids gather on the soft shoot tips and flower buds as growth speeds up in spring. A small colony is easily rubbed off by hand or blasted off with a jet of water, and ladybugs, lacewings and hoverfly larvae usually arrive to deal with the rest if you avoid broad-spectrum sprays. Plants fed heavily with nitrogen attract far more aphids, which is one more reason to keep feeding light.
Thrips are tiny and hard to see, but the damage is distinctive: silvery streaks and flecks on the petals and buds that open twisted or discolored. They build up in warm, dry weather. Remove damaged flowers promptly, keep the plants from getting drought-stressed, and use blue sticky traps to monitor them. An insecticidal soap sprayed into the buds helps if numbers are high.
Prevention in short
Grow godetia in full sun, in limed, free-draining soil, at the right spacing, with a light hand on water and nitrogen. Rotate its position from year to year, clear away collapsed plants promptly, and check the bed often from the moment buds appear.
Slugs and snails can graze autumn-sown seedlings through a mild wet winter, so keep an eye on young rosettes and use traps or barriers if you see damage. Once the plants are a few inches tall they are rarely troubled.