Monday, June 29, 2015

The NMSU Plant Diagnostic Clinic Goes Social

Now there are even more ways to get timely, up-to-date, pest information. After dangling our feet in the pool with Facebook, the NMSU - Plant Diagnostic Clinic has decided to dive head first into the deep end of the "Social Media scene" and Go Social! We are pleased to announce that you can now obtain information from a variety of Social Media sources. You can subscribe to our Blog, like us on Facebook, follow us on Twitter, and pin us on Pinterest! We hope that you'll find these resources are a great way for you to obtain valuable information and that you'll share these links with clientele and friends who may be interested in following us on Social Media.

Don't forget to check out the NMSU Plant Diagnostic Clinic Webpage for more resources on pest identification and pest management.
The header from the NMSU Plant Diagnostic Clinic Blog
Header from the NMSU Plant Diagnostic Clinic Blog

Nutsedges Invade Turf and Ornamental Plantings

Picture of a nutsedge plant growing in gravel
Nutsedge in the landscape
(Photo:  Leslie Beck, NMSU)
Featured Diagnosis: Nutsedge (Cyperus spp.) is a perennial with triangle-shaped stems and long grass-like leaves that appear very shiny in direct sunlight. There are two types of nutsedges: purple (C. roundus) and yellow (C. esculentus), though both are very difficult to control. The plant germinates in the late spring or early summer from underground 'nutlets' or tubers that grow at the end of aggressive rhizomes. The tubers of both nutsedges have the capabilities to survive many years beneath the soil surface. Both purple and yellow nutsedge can outcompete desirable plants and are very tolerant of intensive management.

Picture of nutsedge plants growing in a lawn
Nutsedge in a lawn
(Photo: Leslie Beck, NMSU)
Picture of nutsedge plants growing around juniper plants in a landscape planter box.
Nutsedge in a landscape planter
(Photo: Leslie Beck, NMSU)
Close-up of yellow flower stalk of nutsedge plant.
Nutsedge flowers
(Photo: Leslie Beck, NMSU)
Brown tuber of nutsedge in the palm of a hand.
Nutsedge tuber
(Photo: Leslie Beck, NMSU)
A hand holding a stem of a nutsedge plant showing the triangular shape of the stem.
Triangular-shaped stem of a nutsedge
(Photo: Leslie Beck, NMSU)

Friday, June 26, 2015

Herbicide Injury on Landscape Plants

Yellow deformed leaves on a sycamore tree
Herbicide injury on
(Photo: NMSU- PDC)
Featured Diagnosis: Herbicide Injury. Beware! Herbicide applications in ornamental and turf settings can have unintended consequences. Many herbicides used to manage broadleafed plants are non-selective and can adversely affect desirable trees and shrubs. Some common symptoms include: leaf deformity (e.g. curling, cupping, twisting, and shortened or lengthened internodes), yellowing, wilting, defoliation and, in severe cases, branch dieback or plant death. The ultimate damage to the plant will depend on several factors including, application rate, environmental conditions and overall plant health. In many cases, the plants will recover with time.

Cupped mulberry leaves
Hervicide injury on mulberry
(Photo: NMSU-PDC)
A tree with yellow leaves on the branches on the side of the tree closest to a sidewalk
Herbicide injury on ash
(Photo: NMSU-PDC)

Flea Beetles

A small metallic beetle on a plant
Flea beetle on Guara (Photo: NMSU-PDC)
Featured Diagnosis: Flea Beetles. Numerous samples of flea beetles (Altica sp.) have recently been submitted for indentification. This 4-5mm metallic beetle, is a hopping but harmless nuisance pest indoors, but outdoors, adults can sketetonize foliage on a variety of garden and landscape plants ranging from evening primrose and Guara to grapes and apples. Like all flea beetles, the upper portions of the hind legs are enlarged and full of muscles, allowing the flea beetle to jump to safety when disturbed. Flea beetles overwinter as adults under plant debris or on weeds and in soil. In early spring they begin feeding on foliage. Females deposit eggs near the soil-line where the larvae emerge in about a week. The larvae are white and worm-like and are found feeding on plant roots. Larvae feed for up to three weeks. They pupate in the soil and the adults emerge in about two weeks. Larvae of most flea beetle species cause little damage to the roots.

Read on for more information

Small metallic beetles feeding on a plant and creating holes in the leaves
Flea beetles and feeding
damage on Guara
(Photo: NMSU-PDC)

A composite photo of a flea beetle. The photo on the left is the upper side of the metallic green beetle and the photo on the right is the underside.
Adult flea beetle (notice the large, muscular, hind legs)
(Photo: NMSU-PDC)

Alfalfa Attacked by Whitefringed Beetles!

An alfalfa field with some yellowing plants in the center
Alfalfa infested with whitefringed beetle
(Photo: NMSU-PDC)
Featured Diagnosis: Whitefringed Beetle (Coleoptera, Curculionidae, Naupactus sp.)

New Mexico alfalfa growers may wonder why some of their recently planted or replanted alfalfa fields have patchy, sparse stands and poor yields despite their best corrective efforts. The answer may be infestation by whitefringed beetle. A relative of alfalfa weevil and clover root curculio, whitefringed beetle is a native of South America. First detected in the southeastern U.S. in the mid 1930's, the pest has been associated with over 385 host plant species, including alfalfa, peanuts, cotton, okra, cowpeas, beans, numerous weed species, plus woody plants such as willow, peach, pecan and even pine. Infestations in New Mexico and elsewhere are probably more widespread than presently recognized because the insect is difficult to detect.

Read on for more information

A composite of two photos of a hand holding the stem of an alfalfa plant infested with a beetle larva
Whitefringed beetle larvae in alfalfa roots
(Photo: NMSU-PDC)
An alfalfa field with a large yellow section in the center
Alfalfa infested with whitefringed beetle
(Photo: NMSU-PDC)

Grasshoppers Feeding on Leaves and Flowers

A large green grasshopper sitting on the stem of a plant
Grasshopper on Guara stem
(Photo: NMSU-PDC)
Featured diagnosis: Grasshoppers. If you're a gardener, you're probably all too familiar with this annoying pest. Grasshoppers invade yards, gardens, and greenhouses, munching on tender foliage and flowers, leaving chewed and tattered plant tissue in their wake. Usually, the damage is relatively inconsequential; however when the insect is present in high numbers, damage can be significant - small seedlings may be completely eaten to the ground! Pesticides are usually not recommended for home gardeners as they only affect the grasshoppers they contact and do not protect from new invaders. These materials may also have an unintended negative effect on beneficial insects. Home gardeners who wish to protect their plants should cover them with insect netting until the grasshoppers are gone.

A composite photo showing tattered leaves of a basil plant eaten by a grasshopper.
Feeding damage on basil caused by grasshoppers
(Photo: NMSU-PDC)

A large brown grasshopper sitting on top of a flower
Grasshopper and feeding
damage on an orchid
(Photo: NMSU-PDC)

Tomato Leaf Spot Diseases

Brown spots on a tomato leaf
Early blight
(Photo: NMSU-PDC)
Featured Diagnosis: Tomato leaf spot diseases - Two different fungi which cause leaf spots on tomatoes have recently been identified in the NMSU Plant Diagnostic Clinic: early blight, caused by Alternaria solani, and Phoma rot, caused by Phoma destructiva. These two leaf pathogens occur under similar environmental conditions and produce similar symptoms on plants. Test, don't guess! A laboratory test is recommended to properly identify the causal agent. Samples can be submitted to the NMSU - Plant Diagnostic Clinic through the County Extension Offices.

For homeowners, cultural practices that reduce humidity and leaf wetness are essential for good management: avoid overcrowding and avoid wetting the foliage. If plants are irrigated in a manner that wets the foliage, water early in the day so that the leaves dry quickly. When conditions are highly favorable for disease development, fungicides may be helpful in reducing the severity of the disease. Both organic and synthetic fungicides are registered to help manage these diseases. If fungicides are used, all label instructions should be followed very carefully. Some tomato cultivars are tolerant of early blight and are recommended in areas where this disease is common.

A tomato plant in a pot with yellowing leaves
Phoma rot
(Photo: NMSU-PDC)
A microscope photo of a egg-shaped brown fruiting body of a fungus with round spores around it.
Pycnidia and spores of
Phoma destructiva,
the causal agent of Phoma rot
(Photo: NMSU-PDC)
A microscope photo of multi-celled, elongate spores.
Spores of Alternaria solani,
the causal agent of early blight
(Photo: NMSU-PDC)

Pinyon Spindle Gall Midge

Featured Diagnosis: Pinyon spindle gall midge----Diptera, Cecidomyiidae, Pinyonia edulicola (larval stage photographed)

This native insect is considered primarily a pest of ornamental pinyon, although it must surely occur in the forest, too. Susceptibility of pinyon trees to these and other needle mining insects varies from one individual tree to another. Some are rarely affected while others sustain lots of needle galls.

A banana-shaped gall on a pine needle
Galls on pinyon needles caused
by pinyon spindle gall midge
(Photo: NMSU-PDC)
A white larva in a pine gall
Larva of a pinyon spindle gall midge
in a pinyon needle
(Photo: NMSU-PDC)

Black Medic

A photo of two plants with a quarter to show size
Black medic (Photo: NMSU-PDC)
Featured Diagnosis: Black medic, Medicago lupulina, is a nonnative annual with clover-like leaves, yellow flower heads, and seed pods that are black at maturity. Black medic is good forage for livestock but is a problem weed in turf. It is also known as black medic, black or hop clover, hop medic, nonesuch, and yellow trefoil.

A plant with clover-like leaves in a lawn
Black medic in a lawn
(Photo: NMSU-PDC)
A green clover-like plant with small yellow flowers
Close-up of black medic
(Photo: NMSU-PDC)

Bermuda Grass Stunt Mite

Featured Diagnosis - Bermuda Grass Stunt Mite (Aceria cynodoniensis). This microscopic mite infects bermuda grass giving the turf a stunted, unthrifty appearance. Upon closer examination the leaves and buds at the node become bushy and malformed. This mite is found in the southern and southwestern parts of the U.S. where bermuda grass is commonly grown.

Bermudagrass with stunted leaves
Bermuda grass infected with Aceria cynodoniensis (stunt mite)
(Photo: NMSU - PDC)

A microscope photo of rectangular shaped mites
Bermuda grass stunt mite, Aceria cynodoniensis
(Photo: NMSU-PDC)

Sclerotinia Stem Rot

A photo of basil plants with brown stem lesions
Sclerotinia stem rot on sweet basil
(Photo: NMSU - PDC)
Featured Diagnosis - Stem rot on sweet basil (Ocimum basilicum) caused by the fungus, Sclerotinia sclerotiorum. Sample submitted in May 2015 from Southern NM. Key plant symptoms: necrotic stem lesions and wilt. Key fungal diagnostic characteristic: dark black overwintering structures called sclerotia. These sclerotia can survive and persist for many years in the soil. Unfortunately, once a plant is infected, there is no cure.
A close-up of a brown lesion on the stem of a basil plant
Stem lesion caused by Sclerotinia sclerotiorum
(Photo: NMSU-PDC)
A petri dish with a white fungus and roundish black fruiting bodies around the upper edge of the dish
Sclerotinia sclerotiorum in culture
(Photo: NMSU - PDC)

Thursday, June 25, 2015

Iron Chlorosis Takes its Toll on Landscape Plants

A yellow leave with green veins
Iron chlorosis on a sweetgum leaf
(Photo: NMSU-PDC)
As the temperatures begin to rise many of our landscape plants will begin to show symptoms of environmental stresses. One of the most common landscape disorders in New Mexico is iron deficiency, also called iron chlorosis. Iron deficiency symptoms typically begin in spring when the plants are leafing out. As summer progresses,
plants left untreated may exhibit severe symptoms and have an overall unthrifty appearance.

Iron Deficiency is one of the most common nutrient deficiencies in 
all sorts of landscape plants. Some of the most commonly submitted plants for diagnosis include: Photinia, willows, mulberry, maples, sycamore, Poplars, roses, apples, pears, Hawthorne, stone fruits and pecan. Iron is a critical element for good growth and green color. Iron may be plentiful in the soil, but it is tightly bound to the soil particles in high pH (alkaline and calcareous) soils. Under these conditions, the iron is 
Chlorotic and necrotic shrubs in a landscape
Iron chlorosis on Photinia shrub>
(Photo: NMSU-PDC)
unavailable for plant use.

The classic symptom of iron deficiency is interveinal chlorosis where the leaf turns yellow and the veins remain green. In very severe cases, leaves may turn white in color or develop necrotic spots,
which can look like a fungal infection, on the affected leaves. Over time, plants which remain untreated will start to dieback, become unsightly in appearance and may eventually die. Symptoms can be exacerbated when shrubs are planted in heavy, poorly drained soils

A Bradford pear tree with yellow leaves in a landscape
Iron chlorosis on a
Bradford pear tree
(Photo: NMSU-PDC)
A close-up of yellow leaves and dead branches on a pear tree
Dieback on Bradford pear
caused by iron deficiency
(Photo: NMSU-PDC)

Root-knot Nematode

Plants with leaves drying up in a landscape
Penstemon infected with
root-knot nematode
(Photo: NMSU-PDC)
Featured Diagnosis: Root-Knot Nematode (Meloidogyne incognita) on Penstemon pseudospectabilis.

Key symptoms: Weak, stressed, dehydrated plants with galls (or knots) on the roots. This nematode causes damage on a wide range of host plants including many ornamental plants, agronomic crops and vegetables.

Root-knot nematodes are microscopic, non-segmented worms that are free-living in the soil as a juvenile. When the nematode infects a host plant, the adult becomes sedentary, feeding in one location in the root. The primary symptom of root-knot nematode is the formation of galls or knots on the root system. The galls or knots are a combination of the female nematode and "giant cells" which develop as a result of nematode feeding.

Roots covered with irregular shaped galls
Galls on roots caused by
root-knot nematode
(Photo: NMSU-PDC)
Damage to infected plants results from the inability of water and nutrients to move up through the knots, resulting in above-ground symptoms similar to those caused by many root-infecting pathogens or environmental factors that reduce water uptake by the plant. Infected plants are generally stunted and have fewer, small, pale, off-color leaves. Infected plants may wilt during the hottest time of the day and recover at night. When plants ar infected in the seedling stage, the result may be plant death. However, when mature plants become infected, plants usually do not die, but they are unthrifty and usually produce fewer flowers and fruit than uninfected plants.

Unfortunately, there are limited control options for root-knot nematode in residential environments. Soil solarization can reduce the nematode population. Rotating the garden to a new location and the use of resistant or tolerant varieties can also help to reduce losses.

Powdery Mildew on Apricot

Apricot fruit with green and red color
Apricot fruit with powdery mildew
(Photo: NMSU-PDC)
Featured Diagnosis - Powdery Mildew on apricot, caused by the fungus, Sphaerotheca pannosa. Key symptom: red ringspots and circular lesions on fruit.

On fruit the disease usually appears as round whitish spots a few weeks after shuck fall. The spots will enlarge to cover much of the fruit. Later, the white mycelium sloughs off to reveal rusty colored round lesions. In some cases the center tissue is unaffected resulting in a ringspot pattern. Diseased leaves develop dry brownish patches covered with a white powdery growth. Infected new leaf tissue is dwarfed and distorted. 
A microscope photo of spores coming out of the edge of a leaf
Spores of powdery mildew on apricot
(Photo: NMSU- PDC)

Sphaerotheca pannosa is one of two species of powdery mildew that infect apricot fruit and leaves in the spring. This fungus does not overwinter on apricot and primary inoculum comes from infected roses in spring. Powdery mildew spores are moved by wind, water and plant-to-plant contact. Once the spores reach susceptible host tissue they will germinate when there is adequate free moisture (high humidity, rain or there splashing water) and begin to colonize the plant tissue. 

Sphaerotheca pannosa spreads to apricots from infected roses. Ensuring that rose plants near susceptible hosts are treated appropriately for powdery mildew will reduce initial inoculum and disease incidence. Other cultural practices which help to reduce the occurrence of the disease include: selectively pruning branches to increase air flow and reducing humidity in the canopy, removing and destroying all fallen plant material on susceptible hosts, maintaining appropriate plant nutrient levels and selectively pruning other trees and shrubs to reduce shading. Contact and systemic fungicides are available when cultural management practices aren’t successful in reducing disease incidence to an acceptable level. Proper timing and through coverage of all above ground plant parts is critical for control.