field.jpg

Oklahoma County Cooperative Extension Service

Ask the Determined Gardener

OSU Extension Center

Freddy Hill, Oklahoma County Extension Master Gardener

Freddy Hill at dg@yahoo.com

2500 NE 63rd Street

OKC, OK  73111

405-713-1125

6-12-2018

 

Ask the Determined Gardener

The summer is dominated by tomato questions. Two are blossom end rot and spider mites:  Blossom end rot is a sign that calcium is not regularly delivered to the growth of the fruit.  Regular watering, without long dry spells, helps with the even growth of fruit.  To avoid the spread of disease pathogens do not water overhead, causing splashing on the leaves.  Spider mites have many generations per year with adults having 8 legs.  They appear most often in low humidity weather.  Yellowish spots on the tops of leaves may be an indicator.  These result from sucking activity on the underside.  Placing a white sheet of paper under a branch while shaking the branch will make mites visible. Too much nitrogen or repeated use of Sevin products can worsen outbreaks.  Once spider mites are identified, a miticide containing Kelthane is very affective, with a follow up treatment 3 to 5 days later.  You should never apply a treatment until the presence a pest or disease is verified.

What is causing dead branches and die-back on my Arizona cypress?   Arizona cypress, Eastern red cedar and others are affected by cankers created by 3 varieties of Sieridim organisms.  Cankers may exhude resin.  There is no cure, but sterile management can have some control.  Using sterilized tools remove and dispose of affected branches.  Provide additional water during times of stress.  Severely affected trees should be removed to reduce spread of the disease to other trees in the area.  Japanese cypress has shown some resistance to this disease.

How do I eliminate crabgrass from my summer lawn?  Crabgrass is a summer annual grassy weed, which can be a persistent problem.  Applying a preemergence product between March 15 through April 1st can prevent germination of last year’s seeds.  Post emergence products containing AMA, DSMA or MSMA  in May or June can decrease this problem weed’s spread.  Do not confuse crabgrass with Dallis grass, which sprouts much earlier, whose radiating stems resemble white or pale spokes of a wheel.  In both cases, if weeds are heavily seeding, it’s best to catch and dispose of grass clippings during these periods.  You may benefit be more frequent mowing or hand removing these grasses.

How do I control fall webworms?  There are 2 similar pests that affect our shade and pecan trees.  Eastern tent caterpillars (Malacosoma americanum) construct thick web structures in forks and crotches of trees.  They feed elsewhere and congregate in their tent at night.  Tent caterpillars produce massive egg cluster on the leaves.  Fall webworms (Hyphantria cunea), create dirty, loosely formed structures over an area of branches.  They eat within this web.  Eggs are laid underground and newly hatched larvae travel into the canopy of the host tree.  Neither does significant economical damage but are very unsightly.  In both cases you can open up the webs and allow birds to eat the larvae, or remove and destroy affected branches by hand.  Insecticides with Bacillus thuringiensis (Bt) are effective on most caterpillars.  Other pesticides may be used but may best be applied by professional arborist due to the size of many trees and the density of the web.  The abundance of these pests vary year to year with some summers showing almost no visible webs.

Document Actions
Oklahoma County Events