Sunday, June 26, 2011

Cool to Hot update

Flea beetles are a concern on tomatoes that were set out in May before weather was settled. These plants were stunted from the cold nights and have struggled to begin rapid growth even with the last week of hot weather.

Key to overcoming flea beetle feeding is to promote rapid growth of transplants and seedlings. Flea beetles jump from the soil and attack lower leaves first (photo right). If a transplant grows rapidly as did this tomato set out June 5 (see photo left), they overcome injury. For details and control suggestions for flea beetles that infest tomato family, cabbage family and other plants, see the CSU Extension fact sheet Flea Beetles.

Cilantro flowering has promoted more questions than usual this season. The quick change from cool to hot weather caused plants to rapidly develop flower stalks. Both temperature and day length influence flowering. In hot weather during the long days of summer, cilantro rapidly produces flower stalks with ferny foliage as opposed to the desireable flat leaves (photo shows both).

Plants induced to bolt produce flowers and set seed in four to six weeks from time of sowing. If you purchase transplants, they can quickly start to flower too. Grow plants in cooler shade to delay flowering. Sow a succession of cilantro seed every few weeks through the summer to produce a constant supply of the herb. In cooler spring weather, cilantro will keep in the leafy stage weeks to a month longer.

Note that if plants go to seed, you can make coriander spice from grinding the seed instead of harvesting cilantro leaves.

Photo credit: Flea beetle injury lower tomato leaves, Tomato transplant outgrowing flea beetle injury, Cilantro - All Carl Wilson

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