Mums.JAllen

Photo by Joan Allen, UConn

 

Chrysanthemum season is upon us. This traditional and beautiful fall flower adds a splash of color when most other garden plants are fading for the season. Chrysanthemums have a long list of potential pest and disease problems but, most often, they are free of problems during their short reign of glory in the fall. This article will cover some of the most common problems, their symptoms and what to do to prevent or minimize them.

Several fungi can cause damage to leaves, flowers, and stems. They can cause spotting of leaves or petals and sometimes dieback of plant parts. The fungal disease ray blight results in spotted or killed leaves and stems along with flowers that may be blackened and deformed on one side. Fungal spore production, spread and new infections are all favored by moist conditions. Practices that minimize humidity and leaf wetness will in turn reduce these diseases. If possible, avoid overhead irrigation by watering at the base of the plant.  If this is impractical, water early in the day to promote rapid drying.  Space plants to allow for good airflow between them. Remove diseased plant parts or severely diseased leaves to protect those remaining. While fungicides are not typically necessary, they may be applied as directed on the label in severe cases to protect other plants.

Chrysanth.rayblight.bugwoodChrys.Rayblightbugwood

Symptoms of ray blight including aborted and damage flowers. Photo credit: Central Science Laboratory, Harpenden , British Crown, Bugwood.org

There are two important rust diseases of chrysanthemum. Symptoms on the upper surface of the leaves are quite similar for the two of them and consist of pale yellow leaf spots. To check for rust, flip the leaves over and look for sporulation.  Brown rust, the most common, will have small mounds of dark brown spores on the underside and white rust would have pale beige to peach colored spore masses.  White rust is important to report to state plant pathologists because it is an introduced and regulated disease.  The objective of these regulations and responses (plant destruction/quarantines) is to prevent this disease from becoming established in the United States. While this disease is primarily found in greenhouse and production facilities, it has been found in the landscape in Connecticut before. To inquire about a possible case, contact the UConn Plant Diagnostic Lab (email: joan.allen@uconn.edu, phone: 860-486-6740).

Chrysanth.brownrust.bugwoodCWRsporesJAllen

Chrysanthemum brown rust spores (left) by Penn State Department of Plant Pathology & Environmental Microbiology Archives, Penn State University, Bugwood.org and white rust pustules (right) by Joan Allen, UConn.

Other problems that can affect the leaves and sometimes other parts include a bacterial leaf spot, foliar nematodes and a number of virus and viroid diseases. Symptoms of bacterial leaf spot of chrysanthemum are tan to dark brown areas that may be bordered by yellowing. Brown areas may be delimited by major leaf veins, giving the spots an angular appearance. Spotting may be associated with wilt or dieback. Spread is via splashing water, infected plant debris, or contaminated tools, hands, etc. Avoid working among wet plants and overhead irrigation. Remove and discard infected plants.

Chrys.bact.spot

Bacterial spot of chrysanthemum. Photo credit: R.K. Jones, North Carolina State University, Bugwood.org

Foliar nematodes are microscopic worm-like organisms that move in a film of water on plant surfaces. They enter leaf tissue through the stomates (pores) and feed and reproduce within the leaves. Their movement within the leaf is restricted by the veins so that damage appears as a patchwork of angular leaf spots. Minimizing leaf wetness will reduce spread. Remove symptomatic leaves if there are only a few; if there are many, it’s best to discard the plant.

Foliar nematode injury on Chrysanthemum. Photo credit: Penn State University, Bugwood.org

Virus and viroid symptoms can include yellowing, stunting, rings or mottled patterns on the leaves, or plant deformity. Many of these pathogens are spread by insects that feed by piercing and sucking sap from the plant. Infected plants should be discarded.

In addition to this already somewhat long list, chrysanthemums may succumb to vascular wilt diseases caused by the fungi Fusarium and Verticillium.  These soil-borne fungi infect via the roots and grow within the plants xylem (conductive tissue) resulting in impaired movement of water and nutrients from the roots to the upper parts of the plant. Symptoms include leaf dieback, often on one side of the plant and sometimes beginning with the lower or older leaves first, wilt, and brown discoloration of the vascular tissue within the lower stem. Because both of these can survive without a suitable host plant in the soil for several years or more, alternative and non-susceptible plants should be planted in affected areas. Many cultivars are resistant to both diseases.

Root rot can affect chrysanthemum and can be caused by both fungi and water molds. Healthy roots should be creamy white and crisp or firm. If the plants are wilting or dying back, a check for brown, soft roots can be done by pulling the plant and inspecting them. Excess soil moisture due to poorly drained soil or overwatering promotes root rot. Avoid planting in poorly drained sites and avoid overwatering.

Quite a few insect and mite pests can occur occasionally on mums, too. Several aphid species are attracted to them and high populations can cause yellowing, stunting or deformed new growth. Many aphids can be removed with a strong spray of water. Other alternatives include insecticidal soap and horticultural oil.

If chewing injury is observed, that could be caused by beetles or caterpillars. For beetles, neem products may repel them from feeding. Caterpillars can be killed using products containing the biocontrol agent Bacillus thuringiensis (Bt).

Four-lined plant bug nymph and typical feeding injury on a leaf.  Photo credit: http://www.extension.umn.edu/garden/insects

 

Several true bugs including the four-lined plant bug and tarnished plant bug feed on mums and many other plants by inserting piercing and sucking, straw-like mouthparts into leaves or stems and withdrawing sap. Tarnished plant bugs sometimes feed just below the flower buds, resulting in wilt of the stem.

Chrysanth.leafminer.bugwood

Chrysanthemum leafminer tunneling. Photo credit: Gyorgy Csoka, Hungary Forest Research Institute, Bugwood.org

 

Winding, irregular tunnels or blotches in the leaves are caused by the chrysanthemum leafminer. This pest is the larval stage of a fly. Insecticides are not generally recommended. Remove affected leaves or squash the miner within the leaf to kill it.

While this may seem like a daunting list of potential problems, I should restate that chrysanthemums in the landscape are usually pretty free from problems. The best ways to minimize the likelihood of trouble are to purchase healthy, vigorous plants free of any evidence of problems and to provide adequate water and an ideal site for the new plants. Once they’re in place, check on them regularly. Spotting signs of a problem early will give you the best chance of stopping it before it does serious damage.

Mid March and warmer weather is descending upon us bringing a few pests currently, and some that will no doubt make a return. Inside our homes, the over-wintering nuisance insects have begun to come out of their hiding spots in attics and wall voids where they spent their winter dormancy. Now they are awake and clamoring to get outside to feed, mate and lay eggs on the their host plants. They fly to the windows and any lights trying to go outside. It is best to open the window and let them go or just vacuum them up. The list of nuisance insects which invade our homes in the fall, sleep off the winter, and awake in the spring are boxelder bugs, Asian lady beetles, leaf footed bugs and the brown marmorated stink bug.

box elder bug on gazebo 10-21-15 Pamm Cooper photo (2).jpg

Boxelder bug, photo p.cooper

AsianLady.jpg

Asian Lady Beetles.

 

Leaf footed bug

Leaf footed bug.

brown marmorated stink bug on gazebo 10-21-15 Pamm Cooper photo (2).jpg

Brown Marmorated Stink Bug, photo p.cooper

Other early season pests can be found in the vegetable garden. Asparagus beetle usually appears a few days after the first spears emerge. However now they are busy feeding below ground on the stems pushing their way up. If stalks curl around above ground, chewing damage by the adult beetle has happened below ground as the stalks were developing. Feeding on one side damages the developing cells, while the other side grows normally causing the distorted shoots. Not much can be done to correct the shape, although the asparagus is still edible, just funny looking. Scout the stalks and bed for the nearby asparagus beetles. Hand pick and squish any or spray with neem oil to reduce feeding.

asparagus beetle damage.JPG

There are two types of asparagus beetles, the common and the spotted.

Another early season pest is flea beetle. They get their common name due to the way they move or jump like a flea. They feed on leafy crops of spinach, lettuce and chard of the cool season crops, and love eggplant, tomato and peppers once the soil is warm enough to accept these transplants. Row covers over the plants will keep them off of the leaves. There is a predatory wasp which does parasitize asparagus beetle eggs. The wasp is metalic green and tiny, about 1/8 inch long. The Latin name of the wasp is Tetrastichus asparagi.

What insects are appearing in you area of the world?

-Carol Quish

 

 

Lots of happenings in the vegetable garden this week as things start to take off. Yellow summer squash and zucchini are starting to produce fruits. The first flowers that appeared were male, identified by their long stems holding the blossom. Female flowers have a small squash shaped ovary at the blossom base, that if becomes pollinated, will grow into a full-sized squash.If the pollination of the female flower does not happen, the tiny squash will drop off. Female flowers appear about a week after the first male flowers are put out by the plant.

Female squash blossoms with a fruit behind it. Photo by C.Quish

Female squash blossoms with a fruit behind it. Photo by C.Quish

Male squash blossom is on the long stem. Photo by C.Quish

Male squash blossom is on the long stem. Photo by C.Quish

At the first appearance of blossoms, the squash vine borer also was seen. The adult is a clear winged moth that lays her eggs on the hollow stems both varieties. The egg hatches into a larva tunneling into the center of the vine, feeding on the inside of the stem and blocking the transmission of water to the leaf and all plant material above their feeding site. The result will be wilting of the plant.

Squash vine borer adults, Jeff Hahn photo, UMN.edu

Squash vine borer adults, Jeff Hahn photo, UMN.edu

Control measures are trapping adults, preventing egg laying, and killing larva once stem is invaded. Trap adults by placing a yellow bowl or container filled with soapy water in the garden. Adults are attracted to the color yellow, will fly to the container where they become trapped in the soapy water. Check for eggs on the stems daily and crush any you find. Some folks wrap stems with aluminum foil to create a barrier to egg laying. If larva are found inside the stem, use a hat pin to poke through the stem into the larva to cause death of the insect while the stem will not be harmed much. Another way is to use a knife to slice lengthwise into the stem, dig out the larva, put the stem sides back together and cover with soil. The plant often recovers. Chemical control includes applying insecticide to the base and stems of the squash plant. This will kill the larva before it has a chance to burrow into the stem. Registered insecticides again the squash vine borer are neem, Surround, permethrin and pyrethrins. Always follow pesticide label directions.

Kale, bok choi and Swiss chard are keeping us in greens. The dreaded small caterpillars are starting to appear. Imported cabbage moth, crossed striped caterpillar and the cabbage looper are all common in Connecticut. Insecticidal soap, Bt and spinosad are organic control measures that work well on the early stages of the caterpillar. Apply at recommend label times to keep up with any new hatchings. Be aware of any white moths flitting around the cole crops to alert you to egg laying and the subsequent caterpillar presence.

Cross-striped cabbagworm larva (Evergestis rimosalis). Clemson University USDA Cooperative Extension Slide Series, www.insectimages.org

Cross-striped cabbagworm larva (Evergestis rimosalis).
Clemson University USDA Cooperative Extension Slide Series, http://www.insectimages.org

Cabbage looper larva (Trichoplusia ni) and feeding damage. David Cappaert, Michigan State University, www.insectimages.org

Cabbage looper larva (Trichoplusia ni) and feeding damage.
David Cappaert, Michigan State University, http://www.insectimages.org

Tomatoes, peppers and cucumbers were planted late as my garden had to wait for other responsibilities to happen before planting took place this year. All seem to be slow due to the colder spring soils, so maybe this is a blessing in disguise and I will have an extended harvest. I plan on planting spinach, lettuce, kale and carrots during August for later season crops. Colder hardy varieties will be selected and I will use row covers later to protect from frosts.

– Carol Quish

Pest - Colorado Potato Beetle Adult, www.uwm.edu

Pest – Colorado Potato Beetle Adult, http://www.uwm.edu

Colorado potato beetle larvae, www.agriculture.purdue.edu larvae

Pest – Colorado potato beetle larvae, http://www.agriculture.purdue.edu larvae

Beetles are fascinating insects with a wide variety of colorful families and species. Some are beneficial, feeding on other insect, while other species are just plain pests. All beetles are in the order Coleoptera. Common among all adult beetles are two pair of wings, with front wings being thickened and leathery that completely cover the membranous hind wings. Adults have large compound eyes and chewing mouth parts.

Beneficial Predator as Adult - Eyed click beetle Photo by Pamm Cooper

Beneficial Predator as Adult – Eyed click beetle Photo by Pamm Cooper

Pest - Wireworms, maine.gov

Pest – Wireworms, maine.gov

 

Beetles have complete metamorphosis containing four life stages; egg, larva, pupa and adult beetle. Larvae have chewing mouth parts, and simple eyes which detect light, dark and movement, but cannot see as well as adult stage with the compound eyes. Different species of beetles differ in larval form. Some are c-shaped grubs with six legs, and others are wireworms with no legs. The common grubs found in the lawns will develop into beetles.

Pest - Japanese Beetle umass.edu

Pest – Japanese Beetle umass.edu

Pest - Japanese Beetle Adult

Pest – Japanese Beetle Adult

Control of all beetles can be achieved by hand picking adults and larval stages. Grubs in turfgrass are treated when grubs are newly hatched during the end of May through July by using Imidacloprid or Chlorotraniliprole as the active ingredient. Parasitic nematodes can be applied to lawns to infect the grubs, eating their insides so they never develop into adult beetles. Milky spore is a bacterial disease that affects only Japanese beetle grubs, although it has limited efficacy here in Connecticut.

In the vegetable garden, monitor known host plants by turning over leaves to look for eggs to crush them by hand. Insecticidal soap sprayed directly on any larvae will kill them by suffocation. Spinosad is an organic insecticide that will kill larval stages, too. Monitor for natural predators that would keep the pest population under control. Using broad spectrum insecticides will kill the good guys as well as the pests.

Carabid beetle Lebia grandis are voracious predators of Colorado potato beetle eggs and larvae. photo by Peggy Greb, extension.psu.edu

Carabid beetle Lebia grandis are voracious predators of Colorado potato beetle eggs and larvae. photo by Peggy Greb, extension.psu.edu

Colorado Potato Beetle Eggs, umass.edu

Colorado Potato Beetle Eggs, umass.edu

 

-Carol Quish