Fall Rainfall an Indicator of a Potentially Significant Curly Top Outbreak Next Year

London rocket (Sisymbrium irio) (Photo: N. Goldberg, NMSU)

Beet Curly Top Virus  on chile peppers
(Photo: N. Goldberg, NMSU)

A wet fall, especially rainfall in October, helps to germinate winter annual weeds. Some of these weeds, particularly those in the mustard family, such as London rocket (Sisymbrium irio), provide an excellent overwintering habitat for the curly top insect vector, the beet leafhopper (Circulifer tenellus). Some of these weeds are also asymptomatic hosts for the Beet Curly Top Virus. Studies at New Mexico State University have shown that severe outbreaks of Beet Curly Top Virus occur in years  with excessive rain the preceding October. Within the last couple of weeks, huge populations of London rocket have developed in Dona Ana County (and probably most other counties in New Mexico). This weed can germinate in high numbers such that it appears like a ground cover. A significant effort to eliminate these weeds now, while they are small, should help to reduce the overwintering sites for the beet leafhopper and subsequently reduce the potential for Beet Curly Top Virus next year.

London rocket (Sisymbrium irio) in an empty lot
 (Photo: N. Goldberg, NMSU)

A dense population of London rocket growing along
a roadway (Photo: N. Goldberg, NMSU)

London rocket in an alfalfa field in the middle of winter
(Photo: N. Goldberg, NMSU)

A beet leafhopper (Circulifer tenellus), the insect vector of the
Beet Curly Top Virus (Photo: J. Shaughney, NMSU)

Beet Curly Top Virus on bean (upper left), pumpkin (upper right),
spinach (lower left), and tomato (lower right)
(photos: N. Goldberg and J. French, NMSU)

NMSU's Extension Service to Hold Plant Clinics in Belen and the Albuquerque Area

Specialist's from the Extension Plant Sciences Department will hold plant clinics at the Belen Growers' Market and two growers' markets in the Albuquerque area this coming weekend. Please come see us at one of the following locations and don't forget to bring your problem plants and insects for identification!

On Friday evening, October 16, the group will be present at the Belen Growers' Market located at Anna Becker Park, on Hwy 309 and Reinken Ave. The market begins at 4:30 PM.  The question-and-answer session will be hosted by four specialists: Carol Sutherland, entomologist; Leslie Beck, weed scientist, and Jason French and Natalie Goldberg, who are experts on plant diseases and disorders. In addition, the county Extension agent, Newt McCarty, will be available to help answer questions.

Belen Growers' Market Plant Clinic Flyer

On Saturday morning, October 17, the group will divide into two and provide plant clinics at two Albuquerque area growers markets. Leslie Beck, Jason French and, Bernalillo County Horticulture Agent, Graeme Davis, will be at the Los Ranchos Growers' Market located at 6718 Rio Grande Blvd. NW starting at 8:00 AM. Carol Sutherland, Natalie Goldberg, and Bernalillo County Agriculture Agent, John Garlisch, will be at the Downtown Albuquerque Growers' Market located at Robinson Park starting at 8:00 AM.

Downtown Albuquerque Growers' Market Plant Clinic Flyer

Los Ranchos Growers' Market Plant Clinic Flyer

Common Pests of Sunflowers

Sunflowers are garden favorites for their festive flowers and tasty seeds---that is, until some common insect pests hijack them.

Sunflower Moth

If a sunflower head looks distorted or ‘dirty’ with webbing and gritty beads on it, it could be infested with larvae of the sunflower moth, Homoeosoma electellum. The larvae consume the developing seedsas well as contaminate the entire head with their silk and frass (poop); this, in turn creates a great environment for fungus growth.

Sunflower moth larvae, Homoeosoma electellum.
(Photo: C. Sutherland NMSU)

Sunflower Stem Borer

The hatchling ‘sunflower stem borer,’ Dectes sp., bores into the pith of its host, weakening the plant and/or the flower stem. Parts of affected plants may wilt permanently, or entire plants may flop over in the wind. This particular larva is the immature stage of a ‘long horned beetle’---NOT a caterpillar.

Sunflower stem borer larvae Dectes sp.
(Photo C. Sutherland NMSU)

For more information about theses sunflower pests please contact Dr. Carol Sutherland.

NMSU's Extension Service to Host Plant Clinics in Lordsburg and the Mimbres Valley

New Mexico State University’s Extension Plant Sciences department will host a Plant Clinic at several farmers’ markets this summer and fall, to help educate the community about horticultural practices and pest management, including identification of insect, weed, and disease problems.

“We encourage anyone who is interested in gardening and has a question that they have not been able to get answered, to come out and visit with us,” said Natalie Goldberg, department head of NMSU’s Extension Plant Sciences. “If they have problem plants or pests that they would like to have identified, they are encouraged to bring us a sample of the plant or pest.”

The question-and-answer sessions will be hosted by three specialists: Carol Sutherland, Extension Entomologist; Leslie Beck, Extension Weed Scientist, and Goldberg, Extension Plant Pathologist. In addition, the county Extension agent will be available to help answer questions.

“Some problems people bring to the clinic might be resolved on the spot, but others might need more background information to complete an answer, so we’ll make sure we have the client’s contact information and specific question written down so we can contact them later,” said Sutherland, who will have a collection of insects on display for additional questions.

Goldberg added they hope to answer most questions but if they can’t, they will either take back samples for further analysis or connect clients with other experts.

“Plant Clinics are a great way to interact with people not familiar with the great variety of information available through the Cooperative Extension Service,” Sutherland said.

Flyer for farmers' Market plant clinic in Lordsburg, NM

Flyer for Mimbres Valley Harvest Festival plant clinic

Shepherd’s purse (Capsella bursa-pastoris)

Shepherd’s purse (Capsella bursa-pastoris) infestation
(Photo L. Beck NMSU)

Featured Diagnosis: Shepherd’s purse (Capsella bursa-pastoris) is a weed that has become well-established throughout the state of New Mexico. Though this weed is generally considered to be a winter annual, its’ ability to tolerate a wide range of temperatures often allows for germination and growth at multiple points throughout the year. Germination generally occurs in the late summer, early autumn, and even in the early spring depending on temperatures and moisture. It can be found in multiple cropping systems including nursery, agronomic and vegetable crops, landscape, horticulture, and roadsides.

The plant initially grows as a basal rosette with leaves that closely resemble those of dandelion as the plant matures. One way to distinguish shepherd’s purse rosette leaves from dandelion is to look at the teeth points on the outer edges (margins) of the leaves. The margin teeth of dandelion tend to point downwards towards the center of the rosette while shepherd’s purse teeth tend to be more rounded when young, and become larger and more deeply toothed (pointed straight) as they mature. 

Additionally the leaves of the shepherd’s purse tend to be smooth to lightly hairy on the top and hairy on the bottom. As the plant matures it forms erect, slender stems that hold the small white flowers and unique fruit pods anywhere from 3 to 18 inches up in the air. The fruit (or seed pods) generally appear from April to September, though temperatures often allow for seed production throughout the year. Fruits are easily identifiable as a triangle-heart-shaped, 2-chambered (separated by a dividing line down the middle), flattened pods that hold numerous seed per chamber. Each plant can produce thousands of dull reddish to yellowish seed capable of surviving for multiple years in the soil.

The fruit can taste peppery and is sometimes added to salad greens as a spice; however, foliage and seeds contain digestive irritants which can cause stomach problems when consumed in higher quantities. Management options like repeated cultivation to prevent seeds from maturing, and manually removing plants (including the shallow taproot) before they produce viable seed, can help maintain small populations in gardens and landscapes. While the rosette foliage might be confused with other members of the mustard family, the flat, heart-shaped pods easily distinguish shepherd’s purse from its’ mustard relatives.

Shepherd’s purse (Capsella bursa-pastoris) rosette stage.
(Photo: L. Beck NMSU)

Shepherd’s purse (Capsella bursa-pastoris) pressed
specimen. (Photo L. Beck NMSU)

Shepherd’s purse (Capsella bursa-pastoris)
fruit (Photo L. Beck NMSU)

Shepherd’s purse (Capsella bursa-pastoris)
inflorescence. (Photo L. Beck NMSU)

Curly Top Virus Strikes Again

Curly Top Virus Strikes Again

Tomato infected with Beet Curly Top Virus
Characteristic symptoms include curled, thickened (stiff) foliage
with purple coloration on the underside of the leaves.
(Photo: N. Goldberg, NMSU - PDC)

Curly top virus (CTV), or beet curly top virus (BCTV) as it is more formally known, is widespread throughout arid and semi-arid regions of the world. The virus is common in the western United States from Mexico to Canada and in the eastern Mediterranean Basin. The virus has a wide host range, causing disease in over 300 species in 44 plant families. The virus appears to be restricted to broad-leafed plants, as no monocotyledonous plants have been identified as hosts for this virus. The most commonly infected hosts include sugar beets (for which the disease was first named), tomatoes, peppers, beans, potatoes, spinach, cucurbits, cabbage, alfalfa, and many ornamentals. The virus also survives in many weeds, such as Russian thistle (tumbleweed) and mustard.

Symptoms vary depending on the host; however, this disease also produces some general symptoms. Other factors that relate to the type and severity of symptom development include virus strain and host physiology. The virus exists in many different strains, which vary in the severity of symptoms produced particularly in relation to the host. Severity of disease is also dependent on the age of the plant when infected. For example, when young plants are infected they will often die shortly after infection. When plants are infected after the seedling stage, the plants survive but are yellow and stunted. Infected leaves of some hosts, particularly tomatoes and peppers, become thickened and crisp or stiff, and roll upward as the petioles curve downward. The leaves turn yellow with purplish veins. Leaves of other hosts such as beets become very twisted and curly. In most cases, yield is reduced, and the fruit that is produced ripens prematurely. The immature, dull and wrinkled fruit is a good diagnostic symptom for tomatoes infected with CTV. If plants are infected after they have begun to set fruit, it is not uncommon to see infected and healthy fruit on the same stem.

Beet Curly Top Virus on chile peppers (Photo: N. Goldberg, NMSU - PDC)

Pumpkin infected with Beet Curly Top Virus
(Photo: N. Goldberg, NMSU - PDC)

Beet Curly Top Virus infected bean next to a healthy bean plant
(Photo: J. French, NMSU - PDC)

Beet Curly Top Virus on spinach (Photo: N. Goldberg, NMSU - PDC)

Plant Clinic Coming to the Farmington Growers' Market

Scenes from the Portales Plant Clinic on August 31, 2015

Scenes from the Clovis Plant Clinic on September 1, 2015

Featured Diagnosis: Bacterial Leaf Spot of Cucurbits

Bacterial leaf spot on pumpkin leaf. Note the yellow halo
surrounding the dark lesion.  (Photo: NMSU - PDC)

Bacterial Leaf Spot of Cucurbits – Bacterial leaf spot of cucurbits is caused by the bacterium, Xanthomonas campestris pv. cucurbitae. This disease causes sporadic losses in cucurbit crops grown in temperate climates. In New Mexico, the disease is not common, but can occur when warm, humid conditions are persistent. The disease attacks a number of different hosts including pumpkin, cucumber, gourds, and summer and winter squash.

Symptoms may appear on both the foliage and the fruit. On the foliage, the disease causes small somewhat round water-soaked lesions on the underside of the leaf. A yellow spot appears on the upper leaf surface. In a few days, the spots turn brown with a distinct yellow halo. The appearance on fruit is variable and depends on rind maturity and how much moisture is present. Initial lesions are typically small, slightly sunken, mostly round spots with a tan to beige center. As the spots enlarge (reaching up to 15 mm in diameter), they become noticeably sunken and the rind may cracks. 

Sunken bacterial leaf spot lesion on pumpkin
(Photo: J. French, NMSU-PDC).

Bacterial leaf spot lesion extends into the seed cavity
 (Photo: N. Goldberg, NMSU-PDC)

Bacterial leaf spot on a white pumpkin
(Photo: J. French, NMSU-PDC)

  

NMSU's Extension Service will host Plant Clinics at the Portales and Clovis Farmers' Markets

NMSU’s Extension Service will bring Plant Clinics to farmers’ markets in Portales and Clovis

New Mexico State University’s Extension Plant Sciences department will host a Plant Clinic at several farmers’ markets this summer and fall, to help educate the community about horticultural practices and pest management, including identification of insect, weed, and disease problems.

“We encourage anyone who is interested in gardening and has a question that they have not been able to get answered, to come out and visit with us,” said Natalie Goldberg, department head of NMSU’s Extension Plant Sciences. “If they have problem plants or pests that they would like to have identified, they are encouraged to bring us a sample of the plant or pest.”

The question-and-answer sessions will be hosted by four specialists: Carol Sutherland, entomologist; Leslie Beck, weed scientist, and Jason French and Goldberg, who are experts on plant diseases and disorders. In addition, the county Extension agent will be available to help answer questions.

“Some problems people bring to the clinic might be resolved on the spot, but others might need more background information to complete an answer, so we’ll make sure we have the client’s contact information and specific question written down so we can contact them later,” said Sutherland, who will have a collection of insects on display for additional questions.

Goldberg added they hope to answer most questions but if they can’t, they will either take back samples for further analysis or connect clients with other experts.

“Plant Clinics are a great way to interact with people not familiar with the great variety of information available through the Cooperative Extension Service,” Sutherland said.

Plant Clinics will be hosted at several Farmers' Markets around the state beginning in Portales (August 31 at 5 PM) and Clovis (September 1 at 5 PM).

Plant Clinics will also be held at the following farmers' markets:
September 12, Farmington, Farmington Farmers’ Market, 9AM
October 9, Lordsburg, Lordsburg Farmers’ Market, 4 PM
October 10, Mimbres, Mimbres Valley Harvest Festival, 10 AM
October 16, Belen, Belen Farmers’ Market, 4:30 PM
October 17, Albuquerque, Downtown Growers Market, 8:30 AM and Los Ranchos Growers Market, 8:00 AM

Flyer for the Farmers' Market Plant Clinic
in Portales, NM

Flyer for the Farmers' Market Plant Clinic
in Clovis, NM

Dr. Carol Sutherland identifies a beetle at a plant clinic in Alamogordo
(Photo: N. Goldberg, NMSU-PDC)

Plant Clinic at the Las Cruces Farmers' Market
(Photo: J. French, NMSU-PDC)

Blossom End Rot

Blossom end rot on peppers (Photo: N. Goldberg, NMSU-PDC)

Featured Diagnosis – Blossom end rot. Every year many home gardeners and commercial growers become concerned about a large tan to black spot on the bottom of fruit, especially on peppers and tomatoes. No fungi, bacteria, or any other living disease organisms are known to cause the condition, and it is not spread from one plant to another. This is “blossom-end rot,” a physiological disorder caused by a calcium deficiency in the developing fruit compounded by an imbalance in water and plant nutrients. It is especially problematic in the heat of the summer. As the weather warms and the plants begin to grow more rapidly, requirements for water and calcium increase. Because calcium is not a highly mobile element, a fluctuation in water availability—even for a short period—can result in a deficiency. It is at this time that fruit begins to show symptoms of blossom-end rot.

The disorder first appears as a brown discoloration on the blossom end of the fruit (the end opposite the stem). On chile fruit, the spot occasionally will be off to the side of the blossom end. The spot enlarges as the fruit matures and may eventually cover up to half the fruit. With age, the lesion tissue becomes sunken and leathery. Eventually, secondary fungi or bacteria may invade the tissue. Secondary invasion results in a black or watery appearance. Affected fruit ripens faster than unaffected fruit.

Blossom end rot on peppers (Photo: J. French, NMSU - PDC)

Blossom end rot on tomato fruit (Photo: NMSU-PDC)

Blossom end rot on pepper fruit (Photo: J. French, NMSU-PDC)

Featured Diagnosis: Crown Gall (Agrobacterium tumefaciens)

 Tree trunk infection by Agrobacterium tumefaciens. Resultant gall
nearly 2 feet across. (Photo N. Goldberg NMSU - PDC)

Crown gall, caused by the soilborne bacterium Agrobacterium tumefaciens, has a wide host range among woody and herbaceous plants. More than 600 plant species in over 90 plant families are susceptible. Some of the most common species affected in New Mexico include: apple, cottonwood, elm, grapes, juniper, pear, poplar, pecan, purple-leaf plum, pyracantha, roses, stone fruits, and willows. The bacterium stimulates host cells to divide and enlarge, causing tumor-like galls to develop. Galls on woody plants usually occur on roots and/or trunks at or just below ground level (the root crown) and at graft unions. The bacterium may become systemic in some host plants and cause galls on trunks, stems, branches and leaves above the root crown. Galls may also develop above the crown by pruning with infested cutting shears. On herbaceous plants, galls form on the roots and stems and, occasionally on leaves. Initially, galls are whitish, soft, and spongy. Later, the gall develops an irregular, rough, corky surface and a hard or woody interior. It eventually turns brown or black and may slough off the plant. Galls increase in size as the plant grows and may be less than an inch in diameter to several feet in diameter. The galls impede water and nutrient movement in the plant. Reduced transport of water and nutrients causes chlorosis, stunting, slow growth, and a general decline in plant health.

Crown gall infection at the graft union on rose.
(Photo N. Goldberg NMSU-PDC)

Root flare infection by crown gall. (Photo: N. Goldberg NMSU-PDC)

Severe crown gall infection on the trunk and
branches of a lime tree.
 (Photo: N. Goldberg NMSU -PDC)

Large galls on peach tree roots caused by
Agrobacterium tumefaciens
(Photo: J. FrenchNMSU - PDC)

Featured Diagnosis: Dodder (Cuscuta spp.)

Large mats of dodder parasitizing weeds on a disturbed
road side site. (Photo J. French NMSU-PDC) 

Environmental conditions across the state are perfect for the parasitic weed, dodder, to germinate and grow. This parasite does not have leaves and cannot produce chlorophyll. As such, it grows on other plants, using them for water, nutrients, and carbohydrates. It is common along road sides, but can also grow on crop and landscape plants. In the spring, dodder seeds germinate near the soil surface and send up slender, thread-like twining stems varying in color from pale green to yellow or orange and without any cotyledons (seed leaves). The slender, leafless, thread-like stem sways or rotates slowly until it touches the stem or leaf of another plant and begins to wind around it. On a host plant, the dodder stem will immediately form small appendages called haustoria (tiny sucker-like roots), which penetrate the stems or leaves so that dodder can extract its necessary growth requirements. Soon after attaching to a host plant, the lower end of the dodder withers and breaks its connection with the ground, while the upper part of the stem grows rapidly, often forming dense stringy masses. However, if the dodder seedlings are unable to contact a susceptible host plant soon after germination, they will not survive. The damage of dodder to the host plant varies from moderate to severe depending on the growth of the host plant and on the number of haustoria attachments to the host plant. Dodder infestations reduce crop yield and increase harvesting costs for crops like alfalfa. 

For more information please visit Dodder (Cuscuta spp.)

Dodder in a native landscape setting. (Photo L. Beck NMSU-PDC)

Dodder haustoria (tiny sucker-like roots) penetrating the stem of a host plant.
The parasite uses these projections to extract the necessary nutrients
to survive. (Photo J. French NMSU-PDC)

Small clusters of dodder flowers forming along the stem. Each flower will
produce a small seed pod with 2 to 4 seeds. (Photo J. French NMSU-PDC)

High Humidity Encourages Turf Diseases

Turfgrass infected by Bipolaris sp. - these photos are the same turfgrass
area photographed 10 days apart (Photos: NMSU - PDC)

Summer rain is a welcome occurrence in the desert, however it can also create a favorable environment for diseases. Recently, conditions have been especially favorable for a few common turfgrass diseases. Leaf spot, melting out and brown patch, have been identified in a number of samples submitted to the plant clinic over the past several weeks. These diseases are caused by common soil-borne fungi that are favored by wet, humid conditions. They can be especially severe when heavy rains follow periods of drought or dry conditions. Leaf spot and melting-out diseases are caused by a group of pathogens that used to be grouped together in the fungal genus Helminthosporium. Two fungi in this group, Bipolaris sp. and Curvularia sp., have been isolated from turfgrass samples in New Mexico. Brown patch is caused by Rhizoctonia solani. Similar environmental conditions favor these diseases and it is not uncommon to find more than one of these pathogens in the same sample. When
environmental conditions are highly favorable for disease development, these diseases can spread rapidly resulting in large areas of blighted turf.

Curvularia spores
(Photo: NMSU - PDC)

Leaf spots
caused by
Bipolaris
(Photo: NMSU-PDC)

Bipolaris spores
(Photo: NMSU - PDC)

Brown patch caused by Rhizoctonia solani
(Photo: NMSU - PDC)

Characteristic hyphae of Rhizoctonia
solani (note the right angle branching)
(Photo: NMSU - PDC)