Common Vegetable Problems 

By Mary Helen Ferguson, Extension Agent, Horticulture

We extension agents continue throughout our careers to get new questions, some of which are quite unusual (we could write a fairly entertaining book, I think).  However, there are certain issues that reoccur time and time again—Leyland cypresses seem to be dying, voles are eating someone’s plants, etc.  In this article, I’m going to talk about a few common vegetable problems and some possible solutions. 

Blossom end rot (BER) on tomatoes is a popular topic of calls.  This occurs when the flower end of the fruit (the end away from the stem) gets a dark, circular area on it and is caused by a lack of the nutrient calcium.  While the lack of calcium is the direct cause, just because one has BER doesn’t mean that they don’t have enough calcium in the soil.  It can also mean that the plant has not gotten enough water or has not gotten water on a regular basis (unlike most nutrients, calcium travels up through the plant with water).  Finally, if there is too much of certain other nutrients in the soil, plants may not be able to take up calcium, even though there is plenty in the soil.  BER affects not only tomatoes but also peppers and watermelons. 

One thing you can do to prevent BER is to lime the soil appropriately.  Lime contains calcium carbonate and is used to adjust the pH of the soil.  To find out how much lime your soil needs, you can get a soil test, available at no fee through the NC Dept. of Agriculture and Consumer Services.   Boxes, forms, and instructions are available at our office.   Contrary to the belief of some, it is possible to apply too much lime, so we suggest finding out what the soil pH is before adding it, if lime has been added to that spot in the recent past.

Since water affects calcium uptake, making sure that the tomato plants get enough water, consistently, can also help prevent BER.  Tomatoes need approximately 1 – 1.5 inches of water, from either rain or watering, per week.  Mulching around the plants can help conserve water in the soil so that it doesn’t dry out as quickly and so that the amount of water available to the plant doesn’t vary as much over time, but keep heavy mulches away from right around the stems of the plants so that they don’t provide an environment favorable to disease. 

To keep from having excessive levels of other nutrients that prevent the plants from taking up calcium, don’t put out too much fertilizer.  A soil test can help you determine how much fertilizer to use.  

If you notice that your tomatoes have BER in the current season, you can take action to prevent all of the fruits from having it by mixing 4 tablespoons of calcium chloride or calcium nitrate in a gallon of water and using this to spray the leaves of the plant two or three time per week.  There are also commercially prepared sprays that are marketed specifically for blossom end rot.  You can use one of these rather than trying to find calcium chloride or calcium nitrate, although they’ll probably be more expensive.  

Another common vegetable problem is squash bugs.  These insects feed on the stems of squash and pumpkin (they’re squashes, too) plants and cause them to collapse.  Other plants in the cucurbit family, like cucumbers and watermelons, may get squash bugs also.  You might have seen the bronze or iridescent-looking eggs of the squash bugs on the undersides of leaves of one of these types of plants.  Squash bugs look different when they are adults (a little over ½ inch long, “dark brownish-gray,” about half as wide as they are long) than when they are “babies” (“green with rose-colored to dark appendages” or “grayish white with dark heads, legs and antennae,” depending on the stage).  (Quotes are from NCSU Insect Note #42: True Bugs in the Field and Garden.)  

One way to deal with squash bugs in small gardens is to pick them and leaves with eggs off of the plants.  You can also put down a small piece of wood or other shingle-like piece of material next to the bases of plants.  Come by in the morning, flip it over, and get rid of bugs that have gathered under it overnight.  I started to suggest “squashing” them, but these insects don’t smell pleasant (according to most tastes, I assume), when that is done.  Finally, there are chemical options, but they’re limited, as squash bugs aren’t the easiest insects to kill, especially when they’re adults.  Products containing malathion or esfenvalerate are options for home gardeners, but make sure the check the label and see if the product can be used on squash plants, or whichever type of cucurbit you’re planning to spray.  With pesticides, “the label is the law.”   

I mentioned that squash bug damage can result in a plant collapsing.  However, I want to note that squash and similar plants can also wilt because of squash vine borer damage [or from lack of water, for that matter].  If you see droppings around the bottoms of plants and evidence that a caterpillar has entered the stem of the plant, the squash vine borer may be your culprit.  If you suspect that this is the case and it seems that the caterpillar is in the part of the stem near the soil, you can use a knife to make a cut into the stem (long-ways), remove the caterpillar, and mound damp soil over the cut so that, hopefully, the vine will heal.  As with many insect and disease problems, moving where you put a certain type of plant from season to season can help with this pest.  For this strategy, crop rotation, to be effective, other types of plants that have the same problem shouldn’t be planted in the same place during the next season, either.  For more information on this, you can give me a call.