Various scenarios can take place when growing mums during these very hot days. Here are a few tips to think about.
If plants are drying out quickly during these very high temperatures, and plants are being watered and fertilized more frequently, growers are advised to reduce fertilizer to 200 ppm (constant feed) and use plain water once a week. This will help to lower risk of high soluble salts. High soluble salts can lead to root injury and Pythium root rot.
Two-spotted spider mites (TSSM) can develop quickly during hot dry weather like we have been having recently. Although we have not seen outbreaks yet this season, it is important to monitor for mites and treat when populations are low if using biological controls. Also, it is important to prevent outbreaks of two-spotted mite infestations prior to fall to minimize infestations next spring.
Expect production areas with black fiber cloth to get hot, again this weekend. Garden mums, flowering cabbage and kale may exhibit signs of wilting during extended periods of 90 plus degree temperatures. Plants wilt when the soil is dry, but wilting will also occur in hot weather which may cause plants to be stressed, or if the roots are damage from a root disease such as Pythium, even if the soil is saturated with water. When the roots stop functioning the plants will show signs of stress by wilting.
Feeding injury caused by Four-lined plant bug is showing up on Shasta daisies, Gentiana and other perennials. Retail customers may confuse the damage with disease. Feeding damage appears as spotting on the upper leaf surface. The adult is greenish yellow with 4 black lines running down the back and about 1/4 in long. The immature stage is bright red or orange with black spots on the segment behind the head. As they mature, a yellow stripe appears on each side of the wing pads. They feed for about 6 weeks and plants often outgrow the damage.
There are a variety of ways to produce garden mums using different pinching and planting strategies. Traditional garden mum production schedules involve planting the end of May or early June and pinching plants two times. The first pinch is given within two weeks of transplanting when roots of the cutting reach the bottom and sides of the container and the tops show 1.5-to 2.0 inches of new growth. The second pinch is given when the axillary shoots from the first pinch are 3 to 4 inches long, usually three weeks later in late June or early July, but prior to July 20th.