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Please Come Back Another Time To Find Out More About Plant Diseases

Plant diseases are caused by infectious organisms known as pathogens, which include fungi, bacteria, viruses, parasitic plants, mites, nematodes and several insects. For the home gardener, control of these diseases can be achieved by using seeds that have been created, or bred, for disease resistance, good garden cultivation, healthy soil and regular plant rotation, and sometimes by the moderate use of pesticides. In general, it is better to prevent the occurrence of disease in your garden in the first place, than to try to treat it once it becomes infected. Good agriculture practices, as described in this website, are essential to proper garden health and sustainability. Since there are many different kinds and types of disease, we have only addressed the more common ones that the home gardener is likely to encounter. Finally, constant vigilance of your garden is needed to spot these diseases when they just begin and to take immediate action.

Diseases And Disorders In Our Veggie Garden

Below we have listed diseases and disorders that we have experienced in our veggie garden in the past:


Tomato Septoria Leaf Spot Disease

Closer Look Of The Imported Cabbage Worm

Characteristics and Symptoms:

  • Soil-borne fungal disease that infects tomato leaves and stems
  • Small spots form on leaves enlarging to 1/8-inch in diameter with dark brown edges and white or gray centers
  • Eventually the leaves will turn yellow then wither and die
  • The disease starts from lower older leaves and continues spreading upward until bush is defoliated
  • Infection usually occurs after plants begin to set fruit
  • Defoliation of the bush effects plant growth and can lead to injury to the tomato's fruit causing sunscald and cracking (See sunscald and cracking below)
  • Fungus is most active when temperatures range from 68 to 77° F when humidity is high and rainfall or over-head watering is used
  • Fungus overwinters on crop residue from previous crops, decaying vegetation and other plants that are related to tomatoes (e.g. eggplant, potatoes or peppers)


  • Crop rotation at least every 3 years
  • Remove and dispose of infected plant material from the garden
  • Do not compost infected plants and fruit
  • Prevent overhead watering
  • Plants should be grown in full sun with adequate space between plants for good air circulation to allow leaves to stay dry
  • Keep plants off the ground by staking or using cages to support plants
  • Water plants earlier in the morning
  • Cover soil below plants with at least 6 inches of mulch or black plastic
  • Purchase seeds from a reliable source
  • Disinfect tools and cages after being in contact with infected plant material prevents the spread of disease

Fungicides for Disease Control (Always read and follow all directions on the label):

  • Chlorothalonil
  • Mancozeb
  • Copper Fungicide

Tomato Blossom-End Rot Disorder

End Rot
Characteristics and Symptoms:

  • Rot first appears as a water-soaked area on the blossom end of the tomato fruit (the bottom end of fruit)
  • Later decay-causing organisms cause a sunken, dark-colored or leathery rot
  • Commonly infects one-third to one-half of the fruit
  • Usually appears on the first fruit of the season
  • Low calcium levels in the soil, drought stress and/or excessive moisture reduces the uptake and movement of calcium into the plant


  • When first planted, encourage the production of a large root system by keeping plants a little on the dry side until they begin to flower
  • When fruit develops, keep soil evenly moist and avoid over watering
  • Maintain even soil moisture by regularly watering plants during dry periods
  • Mulch plants with a 3–4 inch layer of organic material to help hold in soil moisture
  • Cultivate about a foot or more away from roots of plant
  • When fertilizing plants, use products that are specifically formulated for tomatoes, follow label instructions
  • Test soil to maintain a pH level of 6.5 to 7
  • Plant varieties that are tolerant to disease


  • When blossom end rot appears on fruit, spray the foliage with calcium chloride or calcium nitrate, follow label instructions
  • Remove and dispose of infected fruit
  • Usually the first few fruits of the season are affected and the condition corrects itself allowing later fruits to develop normally

Tomato Growth Cracks Disorder

Circular Lateral

Characteristics and Symptoms:

  • Two types of growth cracks
  • Concentric cracking is splitting on the surface of the fruit in circular patterns around the stem (tomato on left)
  • Radial cracking is splitting that radiates outward from the stem end of the fruit (tomato on right)
  • Depending on the cultivar, the cracks form when they near maturity
  • Drought followed by heavy rain or watering encourage rapid growth during ripening stage
  • Cracks on fruit may become deep enough so as to allow decay organisms to enter into the fruit and cause fruit to rot


  • Grow cultivars that are tolerant to cracking
  • Maintain even soil moisture with regular watering
  • Mulch plants
  • Avoid heavy nitrogen applications
  • Grow smaller or medium tomatoes instead of large varieties


  • Harvest cracked fruit before fruits decay
  • Maintain even watering of plants

Tomato Sunscald Disorder

Characteristics and Symptoms:

  • Occurs on fruits that are exposed to the direct rays of the sun
  • The condition is more prevalent on plants that have sparse foliage or have leaves that were defoliated by insect pests or diseases
  • Fruit develops a pale yellow to white spot on the side that faces toward the sun
  • Later this area becomes grayish-white in color, flattened and has a paper like texture
  • Fruits can decay from fungus and bacteria, causing the fruit to rot


  • Control leaf diseases on plants (see Tomato Septoria Leaf Spot, Prevention above)
  • Avoid over pruning leaves on plant
  • Maintain healthy foliage with proper watering and fertilizing with a low nitrogen or slow release fertilizer at planting and at full blossom


  • Block out sun's rays on fruit with a light weight material or row cover
  • Harvest fruits at first sign of damage and continue ripening inside your home
Additional information on tomato diseases:

(More plant diseases coming soon)


"Watch Our Garden Grow"

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